High Performance RF Quadrature Low IF Transceiver IC * 48-pin VQFN (Q3)
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Product Description

The CMX991 is a single-chip, high performance, RF transceiver that provides the core functions required to implement a full-featured radio transmitter and receiver. It operates from 100MHz to 1GHz and its I/Q architecture supports multiple modulation types and bandwidths with a single radio design. The half-duplex CMX991 integrates Tx modulators, Rx demodulators, IF PLL and IF VCO subsystems to minimise the external circuits needed when implementing a complete transceiver. User-selected modes suit different application requirements.

The Tx path includes an I/Q modulator to accurately generate modulation at the IF frequency, which may then be translated to the final RF frequency by an integrated image-reject up-converter system. The I/Q modulator IF output is also made available for conversion to RF via external circuits, if desired.

The Rx path includes an integrated 1st Rx mixer having two outputs to support two external 1st IF filter choices, then an integrated 2:1 input mux followed by VGA and wideband signal level measurement functions, to support AGC implementation. The 1st IF signal is then either I/Q demodulated to Zero-IF or mixed to a Low IF output. The CMX991 provides differential and single-ended Rx output options and differential amplifiers for flexible signal conditioning.

The CMX991 operates from a single 3.3V supply over a temperature range of -40°C to +85°C and is available in a 48-pin VQFN (Q3) package.


  • RF mixer with output select
  • 1st IF input select
  • Selectable low IF outputs (450kHz/455kHz)
  • Selectable low IF outputs (450kHz/455kHz)
  • 1st IF Variable Gain Amplifier (VGA)
  • 1st IF Signal Level Indicator (SLI)
  • Two-mode demodulator
  • I/Q Zero-IF with differential outputs
  • I/Q modulator to IF
  • Image-reject up-converter
  • IF and RF outputs
Voltage:3.0 to 3.6 VDC
Form factor:48-pin VQFN
Temperature:-40 to +85 °C
Dimensions:7.0 x 7.0 x 0.9 mm
Current:154 mA
Reference Frequency Input:5 to 30 MHz
Local Oscillator Input:50 to 1150 MHz
RF/IF Input:100 to 1000 MHz
RF/IF Output:100 to 1000 MHz
On-Chip PLL:yes
On-chip VCO:yes
OP Power:-10 dBm
Noise Figure:13dB
Input Bandwidth:135 kHz / 1.4 MHz
C-BUS (SPI) Control Interface:yes