Patent ID: 7974333
Filing Date: 2011-07-05
Classification: H03L,H04B

Abstract:
1. A semiconductor apparatus comprising: a signal source that outputs a signal of predetermined frequency; a frequency divider that receives the output signal of the signal source, and is capable of switching the output signal to two or more frequency division ratios; a frequency detector that detects a frequency of the signal input to the frequency divider; a delta-sigma modulator that controls the frequency division ratio of the frequency divider; and a bandpass filter that receives an output of the frequency divider, wherein a frequency of the input signal of the frequency divider is divided by the frequency division ratio controlled by the delta-sigma modulator, the frequency division ratio of the frequency divider is adjusted according to a detection output of the frequency detector and quantization noise appearing in the output of the frequency divider generated by the delta-sigma modulator is attenuated with the bandpass filter.