Phase locked loop consists of phase detector, filter loop and oscillator into which current is coupled, which is proportional to current pulse provided at output of phase detector

摘要

The phase locked loop includes a phase detector (1) followed by a filter loop (2). The filter has an operational amplifier (20) with switching units (25,26) and capacitive elements (23,24) for storing a current pulse (Ip), which is provided at the output of a phase detector. The operational amplifier provides a proportional current (Iprop), whose amplitude is constant over a clock period, from a current pulse coupled in one of the capacitive elements. An oscillator, in which the proportional current is coupled, is provided after a loop filter.