Phase-locked loop circuitry to generate an output
signal, the phase-locked loop circuitry comprising oscillator circuitry, switched
resistor loop filter, coupled to the input of the oscillator circuitry (which, in one embodiment, includes a
voltage-controlled oscillator), including a switched
resistor network including at least one
resistor and at least one
capacitor, 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 (wherein pulse width and frequency (or period) are pulsing properties of the
control signal),
phase detector circuitry, having an output which is coupled to the switched resistor
loop filter, to generate the
control signal (which may be periodic or non-periodic). The phase-locked loop circuitry may also include
frequency detection circuitry to provide a lock condition of the phase-locked loop circuitry. 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, (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, and (iii) a
switched capacitor network including at least one
capacitor.