The ADMV4540 from Analog Digital is a Quadrature Demodulator that operates in the K-band from 17 to 22 GHz. It has an RF front-end that consists of two low noise amplifier (LNA) paths, each with an optimal cascaded, 5 dB, double-sideband noise figure at maximum gain. The dual paths allow support for antenna polarization. Each channel is capable of rejecting large, out-of-band interferers while reliably boosting the wanted signal which reduces the bandwidth and resolution requirements on the analog-to-digital converters (ADCs) of the system. The excellent matching between channels and their high spurious-free dynamic range (SFDR) overall gain and bandwidth settings make this demodulator ideal for satellite communication systems with dense constellations, multiple carriers, and nearby interferers.
The ADMV4540 has an integrated fractional-N phase-locked loop (PLL) and a low phase noise voltage-controlled oscillator (VCO) that generates the necessary on-chip local oscillator (LO) signal for the two double balanced I/Q mixers, eliminating the need for external frequency synthesis. The VCO utilizes an internal automatic calibration routine that allows the PLL to select the necessary settings and lock.
This quadrature demodulator can be controlled via a 4-wire SPI interface. It requires a DC supply of 3.3 V and consumes less than 3.2 W of power. The ADMV4540 is available in an LGA package that measures 7 x 7 mm and is ideal for satellite communications applications.
