PA Temp Reverse Power Forward Power measure forward power VCO TCXO LO Clock Main PLL IF Clock Main PLL /2 Main LO Reference Clock In Aux PLL Aux PLL measure reverse power ADC and DAC (auxiliary functions) Temp TXCO Control Reference Dividers 4 Auxiliary DACS 6 Auxiliary ADCs Synthesiser Forward Power Auxiliary ADCs and DACs Data VCO PA Control Internal Control, Communication and Data Bus Baseband Clock /2 Reverse Power I Tx Offset PLL Modulation Tx Limiter In Q /4 VCO Temp T Tx Phase Detector Tx Out Rx RF LNA On 90 0 IF Circuits Channel Select and Image Reject Level Track Q Rx F SYNC Detect Frequency Measurement AGC with Gain Control 135 Data Buffer DPLL Demodulator Digital Channel Filter ADC Balun Rx Input Frame Header Digital Channel Filter ADC Offset 45 Rx DAC Offset I /2 R LNA Modulator Tx IF Filter Lock PA DAC Address /1 or /2 Loop Mixer Out Internal Bus RSSI Measurement Power and Regulation CMX990 IF Filter CMX990 Functional Block Diagram Bias Tx Regulated Output Rx IF Rx RF Digital Analogue Supply (VDD/Vss) Control GMSK Baseband Modem 0 Interfaces, Registers and Bus Access 90 Frame Assembly /1 or /2 Frame Disassembly Tx (VCO) Feedback Interface Synthesiser VCO Charge Pump External Regulator Control