Advanced Digital-Radio Baseband Processor A Software-Defined Radio Baseband Processor IC INNOVATIONS INV/TwoWay/981/1 March 2004 Combination Full-Duplex Voice-Codec and Digital Signal Processor IC A-to-D and D-to-A Interfaces n Software-Defined Radio (SDR) Processor IC n Multi-Mode Digital/Analogue PMR and Trunked Radio n High Integration Saves Cost, Space, Power and Design Time n Programmable Flexibility Enables Use in Many Radio Systems n Transmit and Receive Analogue and Digital Processing - Tx and Rx programmable multi-tap FIR filters n Exceptional Rx SINAD Performance n Full-Duplex Voice Codec with Input and Output Gain Setting and Speaker/Earpiece Power Amplifiers n Flexible Serial Interfaces for Multi-Processor Operation n Auxiliary ADCs and DACs for Ancillary Radio Functions n Autonomously Performs Many Critical DSP Intensive Functions SUITABLE APPLICATIONS n Low-Power 2.5V Operation TETRA - APCO25 - Tetrapol - RCR STD-39 - ARIB STD-T61 - ARIB STD-T85 n EV9810 EvKit Available . and many other digital radio systems CML Microcircuits Two-Way Radio COMMUNICATION SEMICONDUCTORS - ‘Communicate’ with CML - Digital Radio* Narrowband digital radio systems provide many advantages over traditional analogue FM RF Modulator Cartesian Loop approaches. By implementing error correction, a digital system can consistently maintain a respectable 'I' Linear PA Voice Coder DAC Channel Coding, RRC ADC Voice Filter p /4 90° operating range even in the presence of significant interference. The majority of current PMR and TDMA Frame DQPSK Formatting DAC trunked digital radio systems deal not only in voice transactions, but also in data, video and still graphics; RRC 'Q' all within a fixed bandwidth. Carrier In the case of voice transactions over a digital system, the digital radio system can provide high-quality Oscillator voice output, even in high noise environments. Local Oscillator Oscillator DAC ADC 'I' Processing RF Amp IF Amp DAC ADC Mod. 90° Tx Radio and Bandpass Interface Filter 'Q' RF Tx Tx Audio Interface Battery Voice Decoder 'I' ADC p /4 DQPSK RRC PA Temp. Voice pi µC DAC Demodulator, Filter Channel Decoder, Ancillary PA Power ADC Tx Radio A theoretical narrowband TDMA Framing RRC 'Q' Analogue and/or Interface CMX981 element Interfaces digital radio implementation DSP AGC CMX981 within a typical (TETRA) digital radio Rx Audio RSSI - the CMX981 performs the majority of baseband processes Interface RF Rx, IF Rx Radio and Interface Demod. Narrowband Digital Radio Standards High Performance Digital Radio voice designs rely on a DSP to perform many of the signal control, TETRA: TErrestrial Trunked RAdio is an open digital trunked radio standard defined by the European encoding, interfacing, routing, level and shaping tasks. Telecommunications Standardisation Institute (ETSI) to meet the needs of digital, cellular, trunked The CMX981 is a truly universal in-phase and quadrature (I and Q) compatible digital radio baseband radio networks. TETRA systems have been, to-date, designed and developed notably as a mobile processor and voice-codec that can be used with many types of analogue and digital modulation system for handling emergency and safety tasks and is widely established in over 55 countries. schemes. With its flexibility, via software definition, the CMX981 can be used in many types of system, APCO 25 (P25) is an open digital radio standard suite specified for high-performance public safety including those operating in: AM and FM modes, and using QAM, BPSK, QPSK, pi/4 DQPSK and FSK radio applications in North America. Supporting both voice and data services the suite includes modulation schemes. several American National Standards Institute (ANSI) approved technical standards developed by The CMX981 goes many steps further in the provision, on chip, of the majority of baseband and system the TIA TR-8 Committee and its subcommittees. interfacing: voiceband digital-to-analogue and analogue-to-digital conversion, Rx and Tx signal shaping P25 Phase 1 radios support both digital and analog FM modulation so they interoperate with legacy via multi-tap digital FIR filters and pi/4 DQPSK modulation. Included on chip is a voice-codec section with analog FM equipment. Spectral efficiency is 1 voice per 12.5kHz RF bandwidth. P25 Phase 2 radios gain control and loudspeaker and earphone amplifiers. In addition to baseband signal path processing, provide 1 voice per 6.25kHz RF bandwidth. the CMX981 offers auxiliary D-to-A and A-to-D functions for the interfacing of other radio operations. In certain public safety bands, FCC rules now require that radios support P25 interoperability mode. The integration of signal processing functions digitally within the CMX981 reduces the load requirements on the host DSP and µC, thus allowing the selection of a lower cost, lower speed and lower powered Tetrapol is a digital trunked radio system based on FDMA access and GMSK modulation. Like its DSP/µC, and releasing the host controller’s time and power for other tasks. competitor, TETRA, Tetrapol is widely used in a large number of countries, predominately in Europe. The CMX981’s default filter co-efficients are aimed at the TETRA standard, but this versatile baseband IC RCR STD-39 is the standard for 400MHz professional digital mobile communication systems can be programmed to operate in many other radio voice and high-speed data systems. Direct access is including TDMA public radio in Japan. available for writing to the I and Q Tx filters; additionally, the pi/4 DQPSK modulator can be bypassed to allow formatted data to be written directly to the signal path. ARIB STD-T61 is the standard for 800MHz digital MCA systems in Japan using p/4 shift QPSK for Flexible clock dividers allow different voice codec and signal codec rates to be accommodated. land vehicles such as taxis. ARIB STD-T85 is the standard for 400MHz and 150MHz Japanese professional digital mobile *For the purposes of this Innovations document, discussions centre around narrowband public and communication systems, including SCPC public radio. private mobile and trunked radio systems. Other radio systems can employ the CMX981. Contents - Digital Radio 2 - Operational Functions 3 - Voice Codec 4 Transmit 5 - Receive 6 - 2 - Control; Power; Interface 7 - Package and Evaluation outside back cover - 2 Operational Functions Microphone 1 Microphone 2 VDDPA EarpieceLoudspeaker VSSPA AUXDAC4 AUXDAC2AUXDAC3AUXDAC1 VSSPA Master (MCLK) Clock In (up to 10MHz) CLOCK GEN CLOCKS Select Serial Interface Clock (Out) 0/20dB (MCLK 0 to 22.5dB MCLK/2 1.5dB Step MCLK/4) 10-bit DAC 10-bit DAC 10-bit DAC 10-bit DAC Decimation Bandpass S-D ADC 0or6dB 0or6dB Filter Filter Symbol Clock PAs (18kHz) Tx (encode) -12.5 to -27.5dB N_IRQ1 1dB Step Sidetone 10-bit ADC N_IRQ2 AUXADC1 Control N_RESET 0 to -30dB 2dB Step SRAM AUXADC2 CBUSEN Interpolation Bandpass S-D DAC AUXADC3 Filter Filter S Sample Rx Ancillary Functions and AUXADC4 (decode) (analogue interfaces) Hold MUX Tone AUXADC5 CMDFS/CCLK Generator Linear Voice Codec (Rx and Tx audio interface) C-BUS AUXADC6 CMDDATI/CDATA / 1 DSP Port CMDRDFSI/CSN Data or Serial CMDRDDATI/RDATA Control µC Fast Transmit Channel and 144kSample/sec Routing for each channel 144kSample/sec 18kSymbol/sec (Tx radio interface) for each channel ITXP Host ficient I and I I I I I ITXN 18kSymbol/sec Q I Coef Q Q Gain, Phase, Q Q 16x4 p /4 DQPSK for each channel RRC Filter Q pi RRC Filter Ramping, Q Reconstruction Outputs FIFO Modulator (79-tap FIR) 0 SD DAC Logic est, and Offset SD QTXP From CMDFS2 T 36kb/sec (63-tap FIR) Filter 4 Data Adjustment Q 2 1 14-bit DAC QTXN Modulator CMDDAT2 Control Direct Write Port and to Access and Interface, Tx Data I o Point Access T CMDRDFS2 Serial 4 Ctrl Point Fast Rx/Tx loopback 4 CMDRDDAT2 (test and monitor) Tx/Rx loopback (test and monitor) 2.304Mb/sec for each channel TXFS I IRXP 3 I I I Q I IRXN TXDAT Rx I 0 Port DATA Q Q Q Q I Q Low Pass Gain Decimation Inputs RRC Filter Q 1 Anti-alias Filter and Offset Filter and SD QRXP Q Serial 144kSample/sec (63-tap FIR) 144kSample/sec Adjustment Vernier Control Filter 4 RXFS for each channel (63-tap FIR) for each channel 16-bit ADC 2 Demodulator Fast QRXN RXDAT and Receive Channel I Ctrl (Rx radio interface) from Serial 4 Interfaces Supply Inputs VDDRX VDDTX VDDIO VDDAUX VDDD VDDD BIAS1 BIAS2 VSSDVDDVC VSSD VSSD VSSAUX VSSTX VSSRXVSSVC - Give us the signal - Let us do the rest - 3 Voice Codec n Encode (Tx) analogue-to-digital conversion with coarse and fine level control n Decode (Rx) digital-to-analogue conversion with level control plus earpiece and loudspeaker PAs n Sidetone facility with level adjust Encode (Tx) Path n Call/user tones available to Rx path n Dual selectable differential microphone sources n Selectable clock/sample rates n Input amp with selectable gain: 0db, 20dB and mute n Fine gain control with 22.5dB range n 14-bit Sigma-Delta analogue-to-digital conversion n Digital encode bandpass filter conforms to CCITT G.712 standard; with Microphone 1 Microphone 2 Loudspeaker Earpiece selectable highpass section n Decimation filter provides (8kHz) data suitable for radio system signal VSSPA VDDPA VSSPA formatting process Select 0/20dB 0 to 22.5dB 1.5dB Step Decimation Bandpass S-D ADC 0or6dB 0or6dB Filter Filter PAs Separate Rx and Tx Paths Tx -12.5 to -27.5dB n Controlled by host via internal registers 1dB Step Sidetone n Configurable to full-duplex operation 0 to -30dB 2dB Step Decode (Rx) Path Interpolation Bandpass S S-D DAC Filter Filter n Data written via serial interface interpolated to 32kHz n Control and Routing Rx Digital decode bandpass filter conforms to CCITT G.712 standard; with selectable highpass section Tone Generator Linear Voice Codec n Level and period adjustable ring-tone generator (0 to 4 kHz) and programmable sidetone path available n 14-bit Sigma-Delta digital-to-analogue conversion n Fine gain control with 0 to -30 dB range n Two selectable output driver (0 or 6 dB) amps: - Differential speaker (130mW into 8W ) - Single-ended earpiece (16.5mW into 32W ) The digitizing voice codec of the CMX981 converts voice signals to and from digital form and can be configured to apply a digital voice filter to meet the G.712 standard.