High linearity I/Q demodulator supports 1GHz bandwidth, achieving up to 60dB image rejection

Analog Devices offers the LTC5594, a wideband, high linearity true zero-IF (ZIF) demodulator with 1GHz instantaneous I and Q 1dB bandwidth. The demodulator is typically capable of 37dB image rejection. Using the on-chip serial port, the device enables correction of the I and Q phase and amplitude imbalance, therefore can be tuned to produce an image rejection of better than 60dB. This option hugely eases calibration while significantly improving receiver performance and decreasing FPGA resources required to null the residual image. Also, the device has integrated baseband amplifiers with adjustable gain, giving a maximum power conversion gain of 9.2dB at 5.8GHz, while delivering 37dBm output IP3 performance. The RF input has an integrated wideband balun transformer, providing single-ended operation with 50Ohm matching from 500MHz to 9GHz. The same input can be matched at lower frequencies from 300MHz to 500MHz by altering one external matching component value. Its high level of integration produces minimum external components and small solution size. The device is provided in a 32-lead, 5mm x 5mm plastic QFN package. The demodulator is powered from a single 5V supply, drawing a nominal 470mA current. The baseband amplifiers can be selectively disabled so that the demodulator can work on 250mA current. An enable pin provides an external controller to shut down the device. When disabled, the device typically draws 20µA supply current.