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InternationalINTERNATIONAL Journal of Electronics and JOURNALCommunication Engineering OF ELECTRONICS & Technology (IJECET), AND ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET) ISSN 0976 – 6464(Print) ISSN 0976 – 6472(Online) IJECET Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME: www.iaeme.com/ijecet.asp © I A E M E Journal Impact Factor (2014): 7.2836 (Calculated by GISI) www.jifactor.com A NEW CIRCUIT MODEL OF LOW VOLTAGE HIGH CURRENT GAIN CMOS COMPOUND PAIR AMPLIFIER Raj Kumar Tiwari, Gaya Prasad Department of Physics & Electronics Dr. R.M.L. Avadh University, Faizabad (U.P.), India ABSTRACT In the Present paper we have studied about a new circuit CMOS Compound pair Amplifier. Proposed new circuit model has been analysed and it is found that proposed circuit has very high current gain and good temperature stability for low voltage applications. CMOS Compound pair can be use as an audio as well as radio frequency tuned amplifier. It is investigated that voltage gain increases from 206.379 to 1740.50 with suitable load values. Gain variations with load resistance from 1K to 100K have been studied in present paper. Variation of input and output impedances have been also studied and it found that CMOS compound pair (Proposed Model) has high input impedance and low output impedance as compare to transistor Sziklai Pair. Key Words: Transistor Sziklai Pair, CMOS Compound Pair, Current Gain, Input and Output, Impedance, Temperature Stability. INTRODUCTION In modern time high bandwidth and gain is a challenging problem of small signal amplification in electronics. Literature surve shows existence of various types of amplifier in which Darlington pair is randomly used for various purposes due its few unique properties. Darlington pair was invented by Bell Laboratories Engineer Sidney Darlington in 1953[1]. It is seen that Darlington pair having large value of β is suitable for small signal and low frequency but not suitable for higher frequency applications [2, 3]. For ready reference value of β is given by equation (1) β= βQ1 * βQ2 + βQ1 + βQ2 (1) Where, symbols have their usual meaning. 65 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME Sziklai pair was named after Hungarian born inventor, George Sziklai. If a compound pair is made with an NPN deriver and PNP output device, then the overall devices behave as NPN bipolar transistor. If a compound pair is made with a PNP deriver and NPN output device, then the overall devices behave as PNP bipolar transistor. Darlington Pair, Sziklai pair having super β value given by equation (2) and CMOS compound pair (proposed new model) is shown in fig.1(a), fig.1(b) and fig.1(c) respectively. β = βQ1 *βQ2 + βQ1 (2) CMOS PNP NPN PNP NPN Collector Collector Drain M3 Collector Collector NPN NMOS PNP Base Base Gate PNP M1 NPN M2 Base PNP PMOS NPN Base PNP PMOS NPN M4 NMOS Emitter Emitter Emitter Emitter Source Darlington Pair Sziklai Pair CMOS Compound Pair (a) (b) (C) Fig. 1: Basic Configuration of Devices; (a) and (b) reference devices and (c) proposed device Complementary metal–oxide–semiconductor (CMOS) uses complementary and symmetrical pairs of p-type and n-type metal oxide semiconductor field effect transistors (MOSFETs) for logic functions. Literature surve[4-18] shows that CMOS devices have high noise immunity and low static power consumption because CMOS devices do not produce as much waste heat as other forms of logic families, like transistor–transistor logic (TTL) or NMOS logic. So in present investigation we proposed a new CMOS compound pair model that works for low voltage and high speed application having high current gain with good temperature stability as compare to reference devices. EXPERIMENTAL CIRCUITS The reference transistor sziklai pair circuit shown in Fig.2 have been simulated having an a.c. input signal 1nVac, Ri=500 ohm, Ci=1µf, R1=47k, R2=5k, Re=2k, Ce=10µf, Co=10uf, Rl=10k, Rc=10k, Vd=5Vdc, and npn transistor Q1=2N2222 and Q2= 2N2904 is used as an active component to design the circuit. Proposed new CMOS circuit shown in the Fig.3 in which the active component transister Sziklai pair is replaced by CMOS compound pair and other passive components are same as taken in fig.2 for ready comperision. 66 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME Fig. 2: Transistor Sziklai pair Circuit (Reference Circuit) Vd 5Vdc 2 2 R1 Rd 47k 10k 1 1 Co Ri Ci M3 10m 1 21 2 MbreakN 500 1uf M1 M2 MbreakP MbreakP V1 1nVac M4 0Vdc MbreakN 2 2 2 2 Rl R2 5k Rs Cs 10k 1 1 2k 1 10uf 1 Fig. 3: Proposed CMOS Compound pair Circuit RESULTS AND DISCUSSIONS Proposed amplifier circuit provides high current gain and wide bandwidth in comparison to reference circuit as shown in fig.4. Proposed new circuit model can be also used as a tuned amplifier for radio frequency application as shown in fig.5. Input Impedance for CMOS compound pair amplifier (proposed model) is found to be higher than transistor sziklai pair as shown in fig.6 fig.7 shows low output impedenceas compare to transistor Sziklai pair amplifier. Fig.8 shows good temperature stability. Present investigation for proposed model shows variation of the gain with load resistance and it is found that gain for proposed model varies from 206.374 to 1740.50 for typical load 1K to 100K respectively which is shown in table 1 for ready reference. Table2 shows variation of gain with respect to the capactancefor fixed load resistance Rl=10k. Analysis shows that for particular value of Co=10pf gain is found to be very high equal to 9606.0. 67 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME Fig. 4: Current gain of transistor Sziklai pair(+ symbol) and CMOS compound pair(x symbol) Fig.5: Voltage gain of transistor Sziklai pair(+ symbol) and CMOS compound pair(x symbol) Fig.6: Input Impedance of transistor Sziklai pair(+ symbol) and CMOS compound pair(x symbol) 68 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME Fig.7: Output Impedance of transistor Sziklai pair(+ symbol) and CMOS compound pair(x symbol) Fig.8: Temperature stable for - 5 to 10 range of CMOS Compound pair TABLES Table 1: Variation of gain with load resistance for capacitance 10uf for CMOS Compound Pair Value of Load Resistance Rl in kiloohm Voltage gain Av in mili 1 206.379 5 279.329 10 369.004 47 984.434 100 1740.50 Table 2: Variation of frequency response with output capacitor for fixed load resistance 10k for CMOS Compound Pair Value of 10 Hz 100 1Khz 10Khz 1 Mhz 1Ghz 1Thz 100Thz Co Hz 10p 314.0 2934.7 9606.0 9543.0 471.3 369.04 369.04 369.04 10n 316.6 4113.5 474.8 369.04 369.04 369.04 369.04 369.04 10u 85.5 340.11 368.6 369.04 369.04 369.04 369.04 369.04 10m 84.9 339.86 368.6 369.04 369.04 369.04 369.04 369.04 69 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 4, April (2014), pp. 65-71 © IAEME CONCLUSION The proposed model can be used for various application due to its high current gain high input impedance and low output impedance and due to its good temperature stability in various analog and digital circuit for low voltage and high speed applications. 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