DC468A

DC468A is a demo board with LT5506 IC. It is a 40MHz to 500MHz monolithic integrated quadrature demodulator with variable gain amplifier (VGA), designed for low voltage operation. It supports standards that use linear modulation format. The chip consists of a VGA, quadrature down-converting mixers and lowpass noise filters. The LO port consists of a divide-by-two stage and LO buffers. The IC provides all building blocks for IF down-conversion to I and Q baseband signals with a single supply voltage of 1.8V to 5.25V. The VGA gain has a linear-in-dB relationship to the control input voltage. Hard-clipping amplifiers at the mixer outputs reduce the recovery time from a signal overload condition. The lowpass filters reduce the out-of-band noise and spurious frequency components. The cut-off frequency of the noise filters is approximately 8.8MHz. The external 2XLO frequency is required to be twice the IF input frequency for the mixers.