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RF Quadrature Modulator/Demodulator

CMX973 - RF Building Block


Features:

  • 20 - 300MHz IF/RF Demodulator
  • 10MHz Rx and 25MHz Tx I/Q Bandwidth
  • 20 - 1000MHz RF Modulator
  • 0dBm Modulator Output
  • < 1 degree I/Q Demod Phase Matching
  • < 0.5dB I/Q Demod Gain Matching
  • IF PLL and VCO amp
  • Low Power Mod/Demod 61mA/15mA @ 3.3V
  • Small 32-pin VQFN Package

Applications:

  • Wireless Data Terminals
  • HF/VHF and UHF Mobile Radio
  • Avionics Radio Systems
  • Telemetry Modems
  • Wireless Microphones
  • Software Defined Radio (SDR)
  • Satellite Terminals

Supply Requirement:

  • 3.0 to 3.6 V power supply

The CMX973 is a high performance quadrature modulator / demodulator featuring a wide operating frequency range and attractive power consumption. Control of the CMX973 may be either by serial bus or by direct control (with reduced functionality).

Programmable features include the local oscillator divider ratio (2 or 4). The small, RF-optimised VQFN package and minimal external components make the device ideal for space-constrained applications.

The CMX973 forms the basis of a high-performance RF transceiver system combining a flexible IF/RF quadrature modulator and quadrature demodulator, in a single chip. Wide signal bandwidth at RF, 0dBm output, low noise and serial bus control delivers maximum flexibility and high-performance, all at an attractive low operating power.

The demodulator is suitable for superheterodyne architectures with IF frequencies of 20MHz to 300MHz and the device may be used in low IF systems or those converting down to baseband.

The modulator converts directly from baseband to the desired transmit frequency 20MHz to 1GHz and features quadrature phase correction to minimise unwanted spectral components. The CMX973 has an on-chip negative resistance amplifier that can form the basis of an on-chip VCO. The CMX973’s quadrature architecture supports a wide range of modulation formats and standards.

The differential inputs are ideal for direct connection to standard modems and interface ICs such as CML’s CMX7163 QAM Data Modem, CMX7164 Multi Mode Wireless Data Modem, CMX910 AIS Baseband Signal Processor, CMX981 Digital Radio Baseband Processor , CMX983 Analogue Front End (AFE) for Digital Radio and CMX7861 Programmable Baseband Interface IC.

Block Image

CMX973 Image Block

Design Support Information

 
Frequency Estimation for a VCO using a Negative Resistance Amplifier Application Note describing how to estimate the operating frequency of VCO designs using a negative resistance amplifier. An Excel spreadsheet that automates the calculation is available below.
Excel Spreadsheet - Frequency Estimation for a VCO using a Negative Resistance Amplifier An Excel spreadsheet that calculates the operating frequency of VCO designs using a negative resistance amplifier. An Application Note describing the process is available above.
 
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