Patent ID: 7863972

Claim:
A continuous-time filter system comprising: a logic unit configured to supply a reference frequency signal based on a clock signal; a master control unit, the master control unit including: an integrator having a transconductor and a capacitor, a voltage comparator having a first input configured to receive a variable threshold voltage, a second input coupled to an output of the integrator, and an output configured to provide an output frequency signal, and a phase frequency comparator having a first input coupled to the output of the voltage comparator to receive the output frequency signal, a second input coupled to a first output of the logic unit to receive the reference frequency signal, and an output configured to provide a control signal; and a slave unit including an input coupled to the output of the phase frequency comparator and a slave filter configured to use the control signal to influence a time constant of the slave filter and therein facilitate calibration of a transfer function of the slave filter.