DIGITAL AUDIO BROADCAST RECEIVER

摘要

This invention relates to a phase locked loop circuit which is particularly suitable for digital audio broadcast (DAB) receiver. A phase locked loop (PLL)(128) for providing a phase locked output signal from a reference signal comprises an input to receive said reference signal; a variable frequency oscillator (132), said oscillator being operable in a selected one of a plurality of frequency bands and having a frequency control input (tune I/P) for controlling a frequency of the oscillator, and a band select input for a band select signal for selecting a said frequency band, and an output for providing said phase locked output signal; and a phase detection system (138), said phase detection system having a first input coupled to said reference signal input, a second input to receive a signal derived from said oscillator output, and an output (139) for providing a frequency control signal to said frequency control input of said oscillator; and wherein said PLL is further configured to adjust a gain of said phase detection system (138) responsive to at least one of said frequency control signal and said band select signal.