CMX975 CML Microcircuits 2.7GHz Up/Down-converter, COMMUNICATION SEMICONDUCTORS LNA, Dual PLL + VCO CMX975 2.7GHz Tx/Rx Mixers, LNA, RF Frac-N Synth, IF Integer-N Synth + VCOs D/975/3 December 2019 DATASHEET Provisional Information Features 1 to 2.7 GHz Up/Down-converter -209dBc/Hz normalised phase noise Configurable image reject or normal mode Rx mixer Integrated low noise LDO regulator Configurable sideband suppression or normal mode Tx Single 2.7V to 3.6V supply mixer 1.8V digital interface supported Combine with CMX973 to implement RF-to-I/Q C-BUS configurable transceiver -40 to +85 operating temp. range 1 to 2.7 GHz RF / 10 to 500 MHz IF Small outline 6mm x 6mm VQFN package Integrated LNA Applications 1.7dB noise figure at 1.5GHz L-Band / S-Band satcom 18dB programmable gain range Military radio RF synthesiser/PLL Wireless microphone Fractional-N 24-bit divider 2.4GHz ISM transceiver Output range 350MHz 3.6GHz Wireless modem Programmable output divider General purpose RF / IF Fast lock function Programmable charge pump current IF synthesiser/PLL Integer-N 14-bit divider Output range 31MHz 1GHz Programmable output divider RF Synthesiser Divide by: 2, 4, 6 or 8 Fractional-N LOOUT PLL Divide by: 1,2,4,6 or 8 MCLK Tx Mixer Divide by: 1, 2 or 4 TXINN TXOUTP TXINP TXOUTN Rx Mixer Divide by: CMX975 1, 2 or 4 RXIFP RFIN RXIFN IF Synthesiser Integer-N PLL Divide by: IFPLLOUT 1, 4, 8 or 16 LNA LNAIN LNAOUT LNASOURCE Power Supply Control Registers C-BUS 2019 CML Microsystems Plc DORF FLCK DOIN LOIN2.7GHz Up/Down-converter, LNA, Dual PLL + VCO CMX975 1 Brief Description The CMX975 is an RF building block IC that provides multiple functions consisting of: RF PLL/VCO, IF PLL/VCO, Transmit Up-convert mixer, Rx Down-convert mixer, and LNA. The RF high frequency synthesiser employs a Fractional-N design and will operate at up to 3.6GHz using a fully-integrated internal VCO or at up to 6GHz with an external frequency source. The IF synthesiser employs an integer-N design and will operate at up to 1GHz. It has an integrated VCO requiring only an external inductor to set the frequency. Internal dividers and buffers are provided for each synthesiser/PLL allowing a wide range of frequency generation options. The Rx mixer can be configured in image reject or normal mode and the Tx mixer can be configured in sideband suppression or normal mode. The integrated LNA offers 18dB of gain reduction in three steps of 6dB. The CMX975 has been designed to work with CMLs CMX973 Quadrature Modulator/Demodulator to provide a simple and cost effective high-frequency superhet transceiver operating in the range 1 to 2.7 GHz. The device operates from a single supply voltage and is available in a small 6x6mm VQFN package. CONTENTS Section Page 1 Brief Description ....................................................................................................................................................... 2 1.1 History ............................................................................................................................................................................... 5 2 Block Diagram .......................................................................................................................................................... 6 3 Performance Specification ........................................................................................................................................ 7 3.1 Electrical Performance ...................................................................................................................................................... 7 3.1.1 Absolute Maximum Ratings .............................................................................................................................................. 7 3.1.2 Operating Limits ................................................................................................................................................................ 7 3.1.3 Operating Characteristics .................................................................................................................................................. 8 4 Pin and Signal Definitions ....................................................................................................................................... 18 4.1 Pin List ............................................................................................................................................................................. 18 4.2 Signal Definitions ............................................................................................................................................................. 19 5 Power Supply and Decoupling ................................................................................................................................ 20 6 Layout Recommendations ...................................................................................................................................... 21 7 Detailed Description ............................................................................................................................................... 22 7.1 Power Management ........................................................................................................................................................ 22 7.2 Clock Generator............................................................................................................................................................... 22 7.3 Tx (Up-conversion) Mixer ................................................................................................................................................ 22 7.3.1 Matching Circuits ............................................................................................................................................................. 25 7.4 Rx (Down-conversion) Mixer ........................................................................................................................................... 27 7.4.1 Matching Circuits ............................................................................................................................................................. 29 7.5 Low Noise Amplifier (LNA) ............................................................................................................................................... 31 7.5.1 LNA S-parameters ............................................................................................................................................................ 31 7.5.2 Matching Circuits ............................................................................................................................................................. 32 7.6 RF VCO and Fractional-N PLL ........................................................................................................................................... 33 7.6.1 RF Fractional-N Synthesiser ............................................................................................................................................. 33 7.6.2 Register Loading Order .................................................................................................................................................... 34 7.6.3 Fractional-N Programming Example ................................................................................................................................ 34 7.6.4 Loop Filter ....................................................................................................................................................................... 35 7.6.5 RF VCO ............................................................................................................................................................................. 36 7.7 IF PLL and VCO ................................................................................................................................................................. 37 7.7.1 IF PLL ............................................................................................................................................................................... 37 7.7.2 Programming Example .................................................................................................................................................... 38 7.7.3 IF VCO .............................................................................................................................................................................. 38 7.7.4 IF PLL Output ................................................................................................................................................................... 40 7.7.5 IF PLL Divider ................................................................................................................................................................... 40 7.8 Local Oscillator (LO) ......................................................................................................................................................... 41 7.8.1 LO Input (LOIN) ................................................................................................................................................................ 43 7.8.2 LO Output (LOOUT) ......................................................................................................................................................... 43 2019 CML Microsystems Plc 2 D/975/3