Patent ID: 6919759

Claim:
A digitally-controlled tuner circuit for tuning a continuous-time filter, said digitally-controlled tuner circuit comprising: a digitally-controlled oscillator receiving a digital control signal, said digitally-controlled oscillator producing an output periodic signal in response to said digital control signal, wherein said digital control signal is composed of a plurality of bits; a square-wave generator coupled to said digitally-controlled oscillator, said square-wave generator receiving said output periodic signal and then converting said output periodic signal into a square wave output periodic signal; a phase/frequency detector coupled to said square-wave generator, said phase/frequency detector receiving a reference signal and said square wave output periodic signal, said phase/frequency detector generating an “up” signal and a “down” signal in response to said reference signal and said square wave output periodic signal; an up/down counter coupled to said phase/frequency detector, said up/down counter producing binary data in response to said “up” signal and said “down” signal; a first decoder coupled to said up/down counter and said digitally-controlled oscillator, said first decoder receiving said binary data and producing said digital control signal in response to said binary data; and a digital filter coupled to said up/down counter, said digital filter receiving said binary data to produce and outputting a first control signal, wherein said first control signal is for tuning the continuous-time filter.