AMPLITUDE CONTROLLED SAWTOOTH GENERATOR

摘要

A sawtooth voltage generator (100) has a first capacitor (156) that is charged with a variable feedback control current to provide a sawtooth output signal with a controlled amplitude. A feedback loop includes a comparator (110) that compares a version of the sawtooth output signal with a fixed voltage reference (Vbg) to provide a comparator output signal (Vcmp) to a phase frequency comparator (112), the output of which controls a source of the variable feedback control current. A method includes controlling the amplitude of a sawtooth output signal by charging a capacitor in a sawtooth voltage generator with a variable feedback control current; comparing a version of the sawtooth output signal with a fixed reference voltage to provide a comparator output signal; processing the comparator output signal in a phase frequency comparator (112) to provide up/down control signals,- and controlling the variable feedback control current with the up/down control signals from the phase frequency comparator.