An experimental, ultra-high-Q, VHF receiver front-end

Techniques recently reported for implementing Q-enhanced monolithic LC bandpass filters are applied to the design of an experimental, low power, ultra-high-Q, VHF receiver front-end. The front-end circuitry includes a tunable, second-order, Q-enhanced preselect filter, followed by a conventional four quadrant active mixer. Received signals at VHF frequencies are translated to a low (⩽1 MHz) IF in a single down conversion. Image rejections approaching 50 dB are obtained without the need for quadrature mixing by operating the preselect filter at an enhanced Q of 10000. The important issues of dynamic range and filter tuning are considered and experimental results are reported for a prototype IC fabricated in a 2 μm BiCMOS process