Jeon (KR); Jang Hong Choi, Daejeon (KR): Ik Soo Eo, Daejeon (56) References Cited (KR); Hyun Kyu Yu, Daejeon (KR) U.S

US009276800B2

(12) United States Patent (10) Patent No.: US 9.276,800 B2 B00 et al. (45) Date of Patent: Mar. 1, 2016

(54) SINGLE FREQUENCY SYNTHESIZER BASED (58) Field of Classification Search FDDTRANSCEIVER CPC ...... H04L27/3836; H04L27/06 USPC ...... 370/280, 281, 29; 455/73 (75) Inventors: Hyun Ho Boo, Incheon (KR); Seon-Ho See application file for complete search history. Han, Daejeon (KR); Jang Hong Choi, Daejeon (KR): Ik Soo Eo, Daejeon (56) References Cited (KR); Hyun Kyu Yu, Daejeon (KR) U.S. PATENT DOCUMENTS (73) Assignee: ELECTRONICS AND 4,061,973 A * 12/1977 Reimers et al...... 455/76 TELECOMMUNICATIONS 4.231,116 A * 10/1980 Sekiguchi et al...... 455/87 RESEARCH INSTITUTE, Daejeon 4,246,539 A * 1/1981 Haruki et al...... 455/76 5,465,409 A * 1 1/1995 Borras et al...... 455,260 (KR) 5,475,677 A * 12/1995 Arnold et al. ... 370,280 5,648,985 A * 7/1997 Bjerede et al...... 375,219 (*) Notice: Subject to any disclaimer, the term of this 5,852,603 A * 12/1998 Lehtinen et al...... 370,280 patent is extended or adjusted under 35 U.S.C. 154(b) by 517 days. (Continued) (21) Appl. No.: 13/608,677 FOREIGN PATENT DOCUMENTS KR 20040065021 A T 2004 (22) Filed: Sep. 10, 2012 WO WO 2009066866 A1 * 5, 2009 ...... HO4B 7,155 (65) Prior Publication Data OTHER PUBLICATIONS US 2013/0064148A1 Mar. 14, 2013 Michiel Steyaert et al., “TP3.3: A Single-Chip CMOS Transceiver for DCS-1800 Wireless Communications'. Digest of Technical (30) Foreign Application Priority Data Papers, Feb. 5-7, 1998, pp. 48-49, vol. 411. Sep. 14, 2011 (KR) ...... 10-2011-0092692 (Continued) May 16, 2012 (KR) ...... 10-2012-OO52200 Primary Examiner – Parth Patel (51) Int. C. (74) Attorney, Agent, or Firm — Rabin & Berdo, P.C. H04 IA02 (2006.01) H04L27/38 (2006.01) (57) ABSTRACT H04L 27/20 (2006.01) The present invention relates to a single frequency synthe H04L 27/233 (2006.01) sizer based FDD transceiver. A single frequency synthesizer H04L27/36 (2006.01) generates and provides a carrier frequency so that frequency HO4B I/OO (2006.01) up-conversion and frequency down-conversion can be per (52) U.S. C. formed at the time of transmission and reception. Accord CPC ...... H04L27/3836 (2013.01); H04L 27/206 ingly, the area, power consumption, and design complexity of (2013.01); H04L 27/2092 (2013.01); H04L the entire system can be reduced, and the performance of the 27/2332 (2013.01); H04L27/362 (2013.01); system can be improved. H04L 27/3854 (2013.01); H04B I/0007 (2013.01) 9 Claims, 8 Drawing Sheets

TRANSMISSION SIGNAL PROCESSOR DIGITAL Has 624 625 BASEBAND ANALOG DIGITAL FRONT RFUP- BANDPASS B> FILTER CONVERTER -END UNIT CONWRTER FILTER

DIGITAL 640 BASEBAND Q ------J| y NFORTION ON

TRANSMISSION IFGENERATION FREQUENCY FREQUENCY AND SVNTHESIZR 630 - DUPLEXER H INFORMTION ON COMPENSTION SN) Lot RECEPTION UNIT 660 FREQUENCY ------sol RECEIVER H US 9.276,800 B2 Page 2

(56) References Cited 2009.00756O1 A1* 3, 2009 Nezhad-Ahmadi et al. ... 455.73 2009.0075612 A1 3/2009 Keehr et al...... 455,226.1 U.S. PATENT DOCUMENTS 2009.0117859 A1* 5, 2009 Smith et al...... 455.78 2009. O130989 A1 5/2009 Rousu et al...... 455/73 5,956,326 9, 1999 Magana ...... 370,277 2009/0168848 A1* 7/2009 Constantinidis et al...... 375,140 6,009,313 12, 1999 Ichiyoshi . ... 455/76 2009/0168849 A1* 7/2009 Rouxel ...... 375,140 6,226,274 5, 2001 Reese et al...... 370,280 2010, 0118744 A1* 5, 2010 Kwon et al. . 370,278 6.256,511 T/2001 Brown et al...... 455,552.1 2010/0135272 A1* 6/2010 Dayal et al...... 370,343 6,449,264 9, 2002 Lehtinen et al. 370,328 2010, O165891 A1* 7, 2010 Lim ...... 370,278 6,501,337 12, 2002 Tucker ...... 331/17 2010/0271953 A1* 10, 2010 Kimetal ... 370,241 7,058,364 6, 2006 Atkinson et al...... 455/76 2011/0216757 A1* 9, 2011 Michel ..... 370/350 7,065.327 6, 2006 Macnally et al...... 455.78 2011/0287711 A1* 1 1/2011 Populus ...... 455,121 7,443,906 10, 2008 Bang et al...... 375,140 7,636,554 12, 2009 Sugar et al. . ... 455.73 OTHER PUBLICATIONS 7,676,244 3, 2010 Park et al. 455,552.1 2001/OO31627 10, 2001 Ries ...... 455,258 Josef Zipper et al., “A Single-Chip Dual-Band CDMA2000 Trans 2006, OO25099 2, 2006 Jung et al...... 455,313 ceiver in 0.13 um CMOS. IEEE Journal of Solid-State Circuits, Dec. 2006/0050810 3, 2006 Haque et al. 375,297 2007, pp. 2785-2794, vol. 42, No. 12. 2006, OO67.429 3, 2006 Beyer et al...... 375,309 2006/0258311 11, 2006 Pestryakov et al. 455,165.1 Darabi, Khorram, Chien, Etc.; "A 2.4-Ghz CMOS Transceiver for 2007/OO995 71 5/2007 Withers et al. 455/67.11 Bluetooth': Journal of Solid-State Circuits; vol. 36, No. 12; pp. 2007/0243832 10, 2007 Park et al...... 455.73 2016-2024; Dec. 2001. 2008/O198776 8, 2008 Seo ...... 370,280 2008/0310318 12, 2008 Bang et al...... 370,252 * cited by examiner U.S. Patent Mar. 1, 2016 Sheet 1 of 8 US 9.276,800 B2

F.G. 1

111 112

TRANSMITTER

DIGITAL FRONT-END DUPLEXER

RECEIVER

113 U.S. Patent US 9.276,800 B2

U.S. Patent US 9.276,800 B2

HEZISEHIN)\S

U.S. Patent Mar. 1, 2016 Sheet 4 of 8 US 9.276,800 B2

PASS DIGITAL FILTER BASEBAND

COS COLOt FREQUENCY 416 SINet SYNTHESIZER

PASS DIGITAL FILTER BASEBAND Q

U.S. Patent Mar. 1, 2016 Sheet 6 of 8 US 9.276,800 B2

079

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0G9 )\ONE|[\ÖEH HEZISEHINXS 099 U.S. Patent Mar. 1, 2016 Sheet 7 of 8 US 9.276,800 B2

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DIGITAL REGON ANALOG REGON BASEBAND -> F F -> RF

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COS COLOt RFOUt SNC) LOt U.S. Patent Mar. 1, 2016 Sheet 8 of 8 US 9.276,800 B2

T\/NOIS HOSSEOOH,

-_JNONO||||NHO-|N|- US 9,276,800 B2 1. 2 SINGLE FREQUENCY SYNTHESIZER BASED Here, an IF may be obtained by a numerically controlled FDDTRANSCEIVER oscillator (NCO)313. A mixer 317 mixes the analog signal with an RF carrier CROSS-REFERENCES TO RELATED generated from a frequency synthesizer 316 and performs APPLICATIONS frequency up-conversion from the mixed signal to an RF band signal. The RF band signal is subject to power amplification The present application claims priority under 35 U.S.C through a PA319 after passing through a bandpass filter 318 119(a) to Korean Application Nos. 10-2011-0092692 and and is then transmitted. 10-2012-0052200, filed on Sep. 14, 2011 and May 16, 2012, The digital-IF structure does not have a problem, such as 10 the leakage of a local oscillator (LO) or a DC offset, as in the Korean Intellectual Property Office, which are incor compared with a direct conversion structure. porated herein by reference in their entirety set forth in full. Meanwhile, in a wireless communication transceiver struc ture, such as that shown in FIG. 1, when reception is per BACKGROUND formed, an RF band signal is received through the antenna 15 115 and the duplexer 114. A receiver 113 performs low-noise Exemplary embodiments of the present invention relate to signal amplification on the RF band signal, performs fre a single frequency synthesizer based frequency division quency down-conversion from the amplified signal to a base duplex (FDD) transceiver, and more particularly, to a single band signal, performs analog signal processing and analog frequency synthesizer based FDD transceiver which enables digital conversion on the baseband signal, and inputs the frequency up-conversion and frequency down-conversion resulting signal to the digital front-end 111. using a single frequency synthesizer at the time of transmis Like the transmitter 112, the receiver 113 also has a direct sion and reception. conversion structure and a digital-IF structure. FIG. 1 shows the construction of a common wireless com As shown in FIG. 4, in the receiver of the common analog munication transceiver, FIG. 2 shows the construction of the circuit-based direct conversion structure, frequency down transmitter of a common analog circuit-based direct conver 25 conversion from an RF band signal to a baseband signal is sion structure, FIG.3 shows the construction of the transmit performed at once. ter of a common digital-IF structure, FIG. 4 shows the con A low noise amplifier (LNA) 411 amplifies the RF band struction of the receiver of the common analog circuit-based signal received from the antenna 115 via the duplexer 114 in direct conversion structure, and FIG.5 shows the construction the state in which low noise remains. Mixers 412 and 413 mix of the receiver of the common digital-IF structure. 30 the amplified RF band signal with carriers generated from a In a wireless communication transceiver structure, Such as frequency synthesizer 416 and perform frequency down-con that shown in FIG. 1, when transmission is performed, a version from the mixed signals to baseband signals. digital front-end 111 performs digital signal processing. A Low pass filters 414 and 415 remove frequency signals that transmitter 112 converts the digital output of the digital front may be aliased from the baseband signals. ADCs 417 and 418 end 111 into analog output, filters an analog baseband signal, 35 convert the respective analog signals into a digital baseband I performs frequency up-conversion into a radio frequency signal and a digital baseband Q signal. (RF) band, and then performs power amplification. Next, a In contrast, as shown in FIG. 5, the receiver of the digital-IF duplexer 114 sends the result signal to an antenna 115. structure performs down-conversion into a low IF band signal The transmitter 112 may include a direct conversion struc and then performs frequency down-conversion from the low ture and a digital-intermediate frequency (IF) structure. 40 IF band signal to a baseband signal again. The direct conversion structure performs frequency up More particularly, an LNA511 performs low-noise ampli conversion into an RF band frequency to be outputted at once. fication on a received signal. Mixers 512 and 513 mix the As shown in FIG. 2, in the transmitter of the analog circuit amplified signal with carriers generated from a frequency based direct conversion structure, digital-analog converters synthesizer 516 and perform frequency down-conversion (DACs) 211 and 212 first convert a digital baseband in-phase 45 from the mixed signals to primary IF band signals. Low pass (I) signal and a digital baseband quadrature (Q) signal into filters 514 and 515 remove aliasing images from the primary respective analog baseband signals. At this time, generated IF band signals. ADCs 517 and 518 convert the analog IF images are removed by low pass filters 213 and 214. band signals into digital IF band signals. A digital mixer 519 Mixers 216 and 217 mix the analog baseband signals with mixes the digital IF band signals and performs frequency respective RF carrier frequencies generated from a frequency 50 down-conversion from the mixed IF band signal into a base synthesizer 215 and perform frequency up-conversion on the band signal again. Here, the IF may be obtained by an NCO I signal and the Q signal. The converted I signal and the S2O. converted Q signal are Summed. The Summed signal is Sub As described above, the wireless communication trans ject to power amplification through a power amplifier (PA) ceiver requires two or more PLL (phase locked loop) fre 219 after passing through a bandpass filter 218 and is then 55 quency synthesizers. In the frequency division dual mode of transmitted. an FDD, a transmitter frequency band and a receiver fre In contrast, as shown in FIG. 3, the transmitter of the quency band are separately set, and a transceiver performs digital-IF structure performs frequency up-conversion from transmission and reception at the same time. Thus, frequency baseband signals to low IF band signals and then performs synthesizers are used in a transmitter and a receiver, respec frequency up-conversion from the low IF band signals to an 60 tively, in order to vary the transmission frequency and the RF band signal again. reception frequency independently. More particularly, mixers 311 and 312 perform frequency That is, each of the transmitter and the receiver of the direct up-conversion from a digital baseband I signal and a digital conversion structure requires one frequency synthesizer, and baseband Q signal into IF band signals in the digital region. the digital-IF structure requires a frequency synthesizer for The IF band signals are summed. A DAC 314 converts the 65 up-conversion from an IF band signal to an RF band signal Summed signal into an analog signal. At this time, a generated and a frequency synthesizer for down-conversion from an RF image is removed by a low pass filter 315. band signal to an IF band signal. US 9,276,800 B2 3 4 Furthermore, a superheterodyne structure is also widely In another embodiment, a single frequency synthesizer used in addition to the direct conversion structure or the based FDD transceiver includes a transmitter configured to digital-IF structure. The superheterodyne structure requires filter an analog baseband signal, perform frequency up-con two frequency synthesizers in each of a transmitter and a version from the analog baseband signal to an RF band signal, receiver. and amplify transmission power of the RF band signal; a As described above, in the FDD system, the transceiver duplexerconfigured to send the RF band signal, amplified by requires two or more frequency synthesizers because trans the transmitter, through an antenna; a receiver configured to mission and reception are performed at the same time and the perform low-noise signal amplification on the RF band signal transmitter and the receiver cannot share the frequency syn received from the antenna via the duplexer, perform fre thesizer unlike in a time division duplex (TDD) system. 10 Accordingly, the FDD system is problematic in that the area, quency down-conversion from the RF band signal to inter power consumption, and design complexity of the entire sys mediate frequency (IF) band signals, and convert the IF band tem are increased. signals into digital IF band signals; a reception signal proces A related prior art includes U.S. Patent Application Publi Sor configured to perform frequency down-conversion from cation No. 2009/0075601, entitled Low-IF Transceiver 15 the digital IF band signals of the receiver to the baseband Architecture (Mar. 19, 2009). signals, Sample the baseband signals, output the sampled baseband signals, receive information on a transmission fre SUMMARY quency and information on a reception frequency, generate an IF for frequency down-conversion from the transmission fre An embodiment of the present invention relates to a single quency and the reception frequency to the baseband signals, frequency synthesizer based FDD transceiver which enables and compensate for the IF of the transmission frequency and frequency up-conversion and frequency down-conversion the reception frequency; and a frequency synthesizer config using a single frequency synthesizer at the time of transmis ured to generate a carrier frequency for the frequency up sion and reception. conversion in the transmitter and for the frequency down In one embodiment, a single frequency synthesizer based 25 conversion in the receiver. FDD transceiver includes a transmission signal processor In the present invention, the transmitter has a direct con configured to perform frequency up-conversion from base version structure or a digital-IF structure. band signals into IF band signals, receive information on a In the present invention, the reception signal processor transmission frequency and information on a reception fre includes an IF down-converter configured to perform fre quency, generate an IF for frequency up-conversion from the 30 transmission frequency and the reception frequency to the IF quency down-conversion from the digital IF band signals to band signals, and compensate for the IF of the transmission the baseband signals; an IF generation and compensation unit frequency and the reception frequency; a transmitter config configured to generate the IF necessary for the frequency ured to convert the digital IF band signals, up-converted by down-conversion from the IF band signals to the baseband the transmission signal processor, into analog signals, remove 35 signals, receive the information on the transmission fre noise from the analog signals, perform frequency up-conver quency and the information on the reception frequency, and sion from the analog signals into RF band signals, amplify the compensate for the IF of the transmission frequency and the RF band signals, and output the amplified RF band signal; a reception frequency; and a digital filter configured to sample duplexer configured to send the RF band signal, outputted the baseband signals converted by the IF down-converter and from the transmitter, through an antenna; a receiver config 40 output the sampled signals. ured to perform low-noise signal amplification on the RF In the IF generation and compensation unit of the present band signal received from the antenna via the duplexer and invention, the compensation for the IF is performed based on perform frequency down-conversion and analog signal pro a difference between the transmission frequency and the cessing on the amplified RF band signal; and a frequency reception frequency. synthesizer configured to generate a carrier frequency for the 45 The carrier frequency generated from the frequency syn frequency up-conversion in the transmitter and the frequency thesizer of the present invention, is a transmission frequency. down-conversion in the receiver. In the present invention, the transmission signal processor BRIEF DESCRIPTION OF THE DRAWINGS includes a digital filter configured to sample the baseband signals and remove sampling images from the baseband sig 50 The above and other aspects, features and other advantages nals; an IF up-converter configured to perform the frequency will be more clearly understood from the following detailed up-conversion from the signals, filtered by the digital filter, description taken in conjunction with the accompanying into the IF bands; and an IF generation and compensation unit drawings, in which: configured to receive the information on the transmission FIG. 1 shows the construction of a common wireless com frequency and the information on the reception frequency, 55 generate the IF necessary for the frequency up-conversion in munication transceiver, the IF band signals, and compensate for the IF. FIG. 2 shows the construction of the transmitter of a com In the present invention, the digital filter up-samples the mon analog circuit-based direct conversion structure; baseband signals. FIG. 3 shows the construction of the transmitter of a com In the IF generation and compensation unit of the present 60 mon digital-IF structure; invention, the compensation for the IF is performed based on FIG. 4 shows the construction of the receiver of the com a difference between the transmission frequency and the mon analog circuit-based direct conversion structure; reception frequency. FIG. 5 shows the construction of the receiver of the com The carrier frequency generated from the frequency syn mon digital-IF structure; thesizer of the present invention is a reception frequency. 65 FIG. 6 shows the construction of a single frequency syn In the present invention, the receiver has a direct conver thesizer based FDD transceiver in accordance with one sion structure or a digital-IF structure. embodiment of the present invention; US 9,276,800 B2 5 6 FIG. 7 shows a construction illustrating frequency up The 200 MHz corresponds to a difference between a carrier conversion in the single frequency synthesizer-based FDD frequency necessary for down-conversion in the receiver 650 transceiverinaccordance with one embodiment of the present and the output frequency of the transmitter 620. invention; and When the reception frequency of the receiver 650 is 2.12 FIG. 8 shows the construction of a single frequency syn GHz and the output frequency of the transmitter 620 is sought thesizer based FDD transceiver in accordance with another to be fixed to 1.95 GHz, the carrier frequency generated from embodiment of the present invention. the frequency synthesizer 660 is changed into 2.12 GHz and the IF of the transmitter 620 is compensated for with 2.12 DESCRIPTION OF SPECIFIC EMBODIMENTS GHz-1.95 GHZ=170 MHZ. 10 When the reception frequency of the receiver 650 is 2.15 Hereinafter, embodiments of a single frequency synthe GHz and the output frequency of the transmitter 620 is sizer based FDD transceiver in accordance with the present changed into 1.97, the IF of the transmitter 620 is compen invention will be described with reference to accompanying sated with 2.15 GHz-1.97 GHZ-180 MHZ and the carrier drawings. However, the embodiments are for illustrative pur frequency generated from the frequency synthesizer 660 is poses only and are not intended to limit the scope of the 15 invention. fixed. FIG. 6 shows the construction of a single frequency syn The above method can also be applied to the case where a thesizer based FDD transceiver in accordance with one digital-IF structure is used in the receiver 650. In this case, a embodiment of the present invention, and FIG. 7 shows a frequency generated from the frequency synthesizer 660 is construction illustrating frequency up-conversion in the used as a carrier frequency that is necessary when the gener ated frequency is down-converted from an RF band to an IF single frequency synthesizer based FDD transceiver in accor band and when the generated frequency is up-converted from dance with one embodiment of the present invention. an IF band to an RF band. When a transmission frequency and As shown in FIG. 6, the single frequency synthesizer based a reception frequency are changed, the IF of the transmission FDD transceiver in accordance with one embodiment of the frequency and the reception frequency is compensated for present invention includes a transmission signal processor 25 610, a transmitter 620, a duplexer 630, a receiver 650, and a according to circumstances. frequency synthesizer 660. The transmitter 620 converts the digital IF band signals, The transmission signal processor 610 includes a digital up-converted by the transmission signal processor 610, into filter 611 configured to sample baseband signals and remove analog signals, removes noise from the analog signals, per sampling images from the baseband signals, an IF up-con 30 forms frequency up-conversion from the analog signals into Verter 612 configured to perform frequency up-conversion RF band signals, and amplifies and outputs the resulting from the filtered signals of the digital filter 611 into IF band signal. signals, and an IF generation and compensation unit 613 To this end, the transmitter 620 includes DACs 621 con configured to generate an IF necessary for the frequency figured to convert the digital IF band signals, subject to fre up-conversion into the IF band signals and compensate for the 35 quency up-converted through the IF up-converter 612, into IF of a transmission frequency and a reception frequency. analog signals, an analog front-end unit 622 configured to Accordingly, the transmission signal processor 610 per remove images from the analog signals outputted from the forms frequency up-conversion from the baseband signals to DACs 621 and control the amounts of the signals, an RF the IF band signals, receives the information on the transmis up-converter 623 configured to perform frequency up-con Sion frequency and the information on the reception fre 40 Version from the IF band signals of the analog front-end unit quency, generates the IF for the frequency up-conversion into 622 into RF band signals, a bandpass filter 624 configured to remove spur and noise on a spectrum from the RF band the IF band signals, and compensates for the IF of the trans signals up-converted by the RF up-converter 623, and a PA mission frequency and the reception frequency. 625 configured to amplify the transmission power of the Here, the digital filter 611 enables the clock frequency of a signal passing through the bandpass filter 624. digital circuit to be operated twice or faster than the IF when 45 up-converting the baseband signals into the IF by up-sam The analog front-end unit 622 removes images generating pling the baseband signals. In this case, an image folding when the analog signals are converted through a low pass problem according to the Nyquist theory, occurring when the filter. clock frequency of the digital circuit does not operate at twice Furthermore, the RF up-converter 623 removes images or higher than the IF, can be prevented. Furthermore, the 50 using an image reject mixer when up-conversion is per digital filter 611 functions to remove sampling images occur formed. ring at positions corresponding to a multiple of a sampling As shown in FIG. 7, frequency up-conversion is performed frequency when performing up-sampling. from a baseband to an IF band, and up-conversion is per The IF up-converter 612 removes images using an image formed from the IF band into an RF band. reject mixer. The IF generation and compensation unit 613 55 A frequency conversion method used in FIG. 7 corre compensates for the IF based on a difference between the sponds to a digital-IF method of embodying the frequency transmission frequency and the reception frequency. up-conversion from the baseband to the IF band in a digital The IF generation and compensation unit 613 compensates manner and embodying the frequency up-conversion from for frequencies when the carrier frequency of the frequency the IF band to the RF band in an analog manner. synthesizer 660 is sought to be changed and the output fre 60 Here, the frequency up-conversion from the baseband to quency of the transmitter 620 is sought to be fixed. the IF band uses an image reject mixer. For example, when the reception frequency of the receiver The diagram shown in FIG. 7 can be expressed by the 650 of a direct conversion structure is 2.15 GHz and the following equation. output frequency of the transmitter 620 of the direct conver RFout I cos () to cos (off-9 coS (olo sin (off--Isin sion structure is 1.95 GHZ, a carrierfrequency generated from 65 (Oro sin (off--Q sin (Diocos (or-I(cos (Orocos the frequency synthesizer 660 is 2.15 GHz and the IF of the (Orthsin (), sin (OF)+O(sin (olo cos (or-cos transmitter 620 is 2.15 GHz-1.95 GHZ=200 MHz. colo sin (of)- cos(Colo-Cott)+Q sin(coto-corr) US 9,276,800 B2 7 8 Accordingly, the final output frequency becomes a desired The frequency synthesizer 860 generates a carrier fre (Oro (O. quency for the frequency up-conversion in the transmitter 810 The duplexer 630 sends the RF band signal, amplified by and for frequency down-conversion in the RF down-converter the PA 625 of the transmitter 620, through an antenna 640. 842. The receiver 650 can have a direct conversion structure or The carrier frequency generated from the frequency syn a digital-IF structure. The receiver 650 performs low-noise thesizer 860 is a transmission frequency. signal amplification on an RF band signal received from the The IF down-converter 842 removes images using an antenna 640 via the duplexer 630 and performs frequency image reject mixer. The IF generation and compensation unit down-conversion and analog signal processing on the RF 852 compensates for frequencies when the carrier frequency band signal. 10 of the frequency synthesizer 860 is sought to be changed and The frequency synthesizer 660 is shared by the transmitter the RF band output frequency of the receiver 840 is sought to 620 and the receiver 650. The frequency synthesizer 660 be fixed. generates a carrier frequency for frequency up-conversion in For example, when the transmission frequency of the trans the RF up-converter 623 and for frequency down-conversion mitter 810 of a direct conversion structure is 1.95 GHz and the in the receiver 650. 15 reception frequency of the receiver 840 of the direct conver The carrier frequency generated from the frequency syn sion structure is 2.15 GHZ, a carrier frequency generated from thesizer 660 is a reception frequency. the frequency synthesizer 860 is 1.95 GHz and the IF of the FIG. 8 shows the construction of a single frequency syn receiver 840 is 2.15 GHZ-1.95 GHZ=200 MHz. thesizer based FDD transceiver in accordance with another When the reception frequency is sought to be changed into embodiment of the present invention. 2.12 GHZ and the transmission frequency is sought to be fixed As shown in FIG. 8, the single frequency synthesizer based to 1.95 GHZ, the IF of the receiver 840 is compensated with FDD transceiver includes a transmitter 810, a duplexer 820, a 2.12 GHz-1.95 GHz-170 MHz and the carrier frequency of receiver 840, a reception signal processor 850, and a fre the frequency synthesizer 860 is fixed. quency synthesizer 860. When the reception frequency is 2.15 GHZ and the trans The transmitter 810 can have a direct conversion structure 25 mission frequency is sought to be changed into 1.97GHZ, the or a digital-IF structure. The transmitter 810 filters an analog carrier frequency of the frequency synthesizer 860 is changed baseband signal, performs frequency up-conversion from the into 1.97 GHZ, and the IF of the receiver 840 is compensated analog baseband signal to an RF band, and performs the for with 2.15 GHZ-1.97 GHZ=180 MHZ. transmission power of the RF band signal. The above method may also be applied to the case where The duplexer 820 sends the signal, amplified by the trans 30 the transmitter 810 uses a digital-IF structure. In this case, a mitter 810, through an antenna 830. carrier frequency necessary when the transmitter 810 up The receiver 840 performs low-noise signal amplification converts an IF band signal into an RF band signal is used as a on the RF band signal received from the antenna 830 via the frequency necessary when the receiver 840 down-converts duplexer 820 and performs frequency down-conversion from the RF band signal into an IF band signal, and an IF suitable the IF band signal to a digital signal. 35 for the signals is used. To this end, the receiver 840 includes an LNA 841 config As described above, in accordance with the single fre ured to amplify the RF band signal received from the antenna quency synthesizer based FDD transceiver according to the 830 via the duplexer 820 in the state in which low noise is present invention, a single frequency synthesizer generates maintained, an RF down-converter 842 configured to perform and provides a carrier frequency so that frequency up-conver frequency down-conversion the RF band signal, Subjected to 40 sion and frequency down-conversion can be performed at the low noise amplification by the LNA841, into IF band signals, time of transmission and reception. Accordingly, the area, an analog front-end unit 843 configured to remove aliasing power consumption, and design complexity of the entire sys images from the IF band signals down-converted by the RF tem can be reduced, and the performance of the system can be down-converter 842, and an ADC 844 configured to convert improved. the signals of the analog front-end unit 843 into digital sig 45 Furthermore, the present invention keeps pace with the nals. flow of the semiconductor industry that tries to maximize the The reception signal processor 850 includes an IF down signal processing of a digital circuit because the role of the converter 851 configured to perform frequency down-conver digital circuit becomes important. sion from the digital IF band signals into baseband signals, an The embodiments of the present invention have been dis IF generation and compensation unit 852 configured to gen 50 closed above for illustrative purposes. Those skilled in the art erate an IF necessary when the frequency down-conversion will appreciate that various modifications, additions and Sub from the IF band signals into the baseband signals is per stitutions are possible, without departing from the scope and formed, receive information on a transmission frequency and spirit of the invention as disclosed in the accompanying information on a reception frequency, and compensate for the claims. IF of the transmission frequency and the reception frequency, 55 and a digital filter 853 configured to sample the baseband What is claimed is: signals converted by the IF down-converter 851 and output 1. A single frequency synthesizer based frequency division the resulting signals. duplex (FDD) transceiver, comprising: As described above, frequency down-conversion from the a transmission signal processor configured to perform fre digital IF band signals, outputted from the receiver 840, to the 60 quency up-conversion from baseband signals into inter baseband signals is performed. The baseband signals are mediate frequency (IF) band signals, receive informa sampled and outputted, and information on a transmission tion on a transmission frequency and information on a frequency and information on a reception frequency are reception frequency, generate an IF for frequency up received. An IF for frequency down-conversion from the conversion from the transmission frequency to the IF transmission frequency and the reception frequency to base 65 band signals, and compensate for the IF based on a band signals are generated, and the IF of the transmission difference between the transmission frequency and the frequency and the reception frequency is compensated for. reception frequency; US 9,276,800 B2 9 10 a transmitter configured to convert the digital IF band Sig a duplexerconfigured to send the RF band signal, amplified nals, up-converted by the transmission signal processor, by the transmitter, through an antenna; into analog signals, remove noise from the analog sig a receiver configured to perform low-noise signal amplifi nals, perform frequency up-conversion from the analog cation on the RF band signal received from the antenna signals into radio frequency (RF) band signals, amplify via the duplexer, perform frequency down-conversion the RF band signals, and output the amplified RF band from the RF band signal to intermediate frequency (IF) signal; band signals, and convert the IF band signals into digital a duplexerconfigured to send the RF band signal, outputted IF band signals; from the transmitter, through an antenna; a reception signal processor configured to perform fre a receiver configured to perform low-noise signal amplifi 10 cation on the RF band signal received from the antenna quency down-conversion from the digital IF band sig via the duplexer and perform frequency down-conver nals of the receiver to the baseband signals, sample the sion and analog signal processing on the amplified RF baseband signals, output the sampled baseband signals, band signal; and receive information on a transmission frequency and a frequency synthesizer configured to generate a carrier 15 information on a reception frequency, generate an IF for frequency for the frequency up-conversion in the trans frequency down-conversion from the reception fre mitter and the frequency down-conversion in the quency to the baseband signals, and compensate for the receiver; wherein the transmission signal processor IF based on a difference between the transmission fre compensates for the IF when the carrier frequency is to quency and the reception frequency; and be changed and an RF band output frequency of the a frequency synthesizer configured to generate a carrier receiver is to be fixed, or when the RF band output frequency for the frequency up-conversion in the trans frequency of the receiver is to be changed and the carrier mitter and for the frequency down-conversion in the frequency is to be fixed. receiver; wherein the reception signal processor com 2. The single frequency synthesizer based FDD transceiver pensates for the IF when the carrier frequency is to be of claim 1, wherein the transmission signal processor com 25 changed and an RF band output frequency of the prises: receiver is to be fixed, or when the RF band output a digital filter configured to sample the baseband signals frequency of the receiver is to be changed and the carrier and remove sampling images from the baseband signals; frequency is to be fixed. an IF up-converter configured to perform the frequency 7. The single frequency synthesizer based FDD transceiver up-conversion from the signals, filtered by the digital 30 of claim 6, wherein the transmitter has a direct conversion filter, into the IF bands; and an IF generation and compensation unit configured to structure or a digital-IF structure. receive the information on the transmission frequency 8. The single frequency synthesizer based FDD transceiver and the information on the reception frequency, generate of claim 6, wherein the reception signal processor comprises: the IF necessary for the frequency up-conversion in the 35 an IF down-converter configured to perform frequency IF band signals, and compensate for the IF. down-conversion from the digital IF band signals to the 3. The single frequency synthesizer based FDD transceiver baseband signals; of claim 2, wherein the digital filter up-samples the baseband an IF generation and compensation unit configured togen signals. erate the IF necessary for the frequency down-conver 4. The single frequency synthesizer based FDD transceiver 40 sion from the IF band signals to the baseband signals, of claim 1, wherein the carrier frequency generated from the receive the information on the transmission frequency frequency synthesizer is a reception frequency. and the information on the reception frequency, and 5. The single frequency synthesizer based FDD transceiver compensate for the IF of the transmission frequency and of claim 1, wherein the receiver has a direct conversion struc the reception frequency; and ture or a digital-IF structure. 45 a digital filter configured to sample the baseband signals 6. A single frequency synthesizer based frequency division converted by the IF down-converter and output the duplex (FDD) transceiver, comprising: sampled signals. a transmitter configured to filteran analog baseband signal, 9. The single frequency synthesizer based FDD transceiver perform frequency up-conversion from the analog base of claim 6, wherein the carrier frequency generated from the band signal to a radio frequency (RF) band signal, and 50 frequency synthesizer is a transmission frequency. amplify transmission power of the RF band signal; k k k k k