Tunable bandpass filter

A single-chip tunable bandpass filter, comprising:

• a plurality of single stage biquad bandpass filter circuits serially coupled on the single-chip, the bandpass filter circuit coupled to a differential input formed on the single-chip and configured to provide a bandpass filtered differential output signal;
• an output buffer configured on the single-chip to provide the bandpass filtered differential output signal to a differential output formed on the single-chip;
• all tuning components for the each of the plurality of single stage biquad bandpass filter circuits formed on the single-chip;
• and
• a tuning input formed on the single-chip and coupled to a data register providing tuning data to each of the plurality of single stage biquad bandpass filter circuits for adjusting the all tuning components for tuning the bandpass filter circuit to a programmed center frequency;
• wherein, no tuning components are external to the single-chip for tuning the bandpass filter circuit to the programmed center frequency.

A method of programming a center frequency of a single-chip tunable bandpass filter having all tuning components located on the single-chip, comprising:

• receiving a serial data stream at a serial programming interface;
• converting the serial data stream to tuning data and storing the tuning data in a data register;
• and
• providing control bits from the data register to each of a plurality of serially coupled single stage biquad bandpass filter circuits to vary a programmable resistor located on the single-chip within each of the serially coupled single stage biquad bandpass filter circuits thereby adjusting the center frequency of the single-chip tunable bandpass filter.