An integrated receiver with channel selection and image rejection
substantially implemented on a single CMOS integrated circuit is
described. A receiver front end provides programmable attenuation and a
programmable gain low noise amplifier. Frequency conversion circuitry
advantageously uses LC filters integrated onto the substrate in
conjunction with image reject mixers to provide sufficient image
frequency rejection. Filter tuning and inductor Q compensation over
temperature are performed on chip. The filters utilize multi track spiral
inductors. The filters are tuned using local oscillators to tune a
substitute filter, and frequency scaling during filter component values
to those of the filter being tuned. In conjunction with filtering,
frequency planning provides additional image rejection. The advantageous
choice of local oscillator signal generation methods on chip is by PLL
out of band local oscillation and by direct synthesis for in band local
oscillator. The VCOs in the PLLs are centered using a control circuit to
center the tuning capacitance range. A differential crystal oscillator is
advantageously used as a frequency reference. Differential signal
transmission is advantageously used throughout the receiver.