Patent ID: 7948286
Filing Date: 2011-05-24
Classification: H03L

Abstract:
1. A loop bandwidth control apparatus, applied to a phase locked loop (PLL) comprising a phase frequency detector (PFD), a charge pump and a voltage-controlled oscillator (VCO), the loop bandwidth control apparatus comprising: a first loop filter module, coupled to the charge pump, that outputs a first voltage; a second loop filter module, coupled to the charge pump, that outputs a second voltage, a bandwidth of the second loop filter module being different from that of the first loop filter module; a control module, coupled to the first loop filter module and the second loop filter module, that generates a bandwidth control signal according to the first voltage or the second voltage; a first switching module, coupled to the control module and the charge pump, that forms a path between the charge pump and one of the first loop filter module and the second loop filter module according to the bandwidth control signal; and a second switching module, coupled to the control module and the VCO, that forms a path between the VCO and one of the first loop filter module and the second loop filter module according to the bandwidth control signal.