Patent ID: 8829959

Claim:
A phase-locked loop circuitry comprising: oscillator circuitry having an input and an output; switched resistor loop filter, having an output which is coupled to the input of the oscillator circuitry, wherein the switched resistor loop filter includes a switched resistor network including a plurality of resistors, a plurality of capacitors and at least one switch, wherein an effective resistance of the switched resistor network is responsive to and increases as a function of one or more pulsing properties of a control signal; phase detector circuitry, having an output which is coupled to the switched resistor loop filter, to generate the control signal; divider circuitry to couple the output of the oscillator circuitry to an input of the phase detector circuitry; and frequency detection circuitry, coupled to the output of the divider circuitry, to provide a lock condition of the phase-locked loop circuitry, wherein the frequency detection circuitry includes: (i) circuitry to generate a signal which is representative of the frequency of the output signal of the phase-locked loop circuitry, and (ii) comparison circuitry to compare the signal which is representative of the frequency of the output signal of the phase-locked loop circuitry to a reference input to the phase-locked loop circuitry.