Patent ID: 6342817
Filing Date: 2002-01-29
Classification: H03K,H03L

Abstract:
A method for generating a high-precision periodic oscillating waveform using an integrating amplifier circuit, the amplifier circuit having a first input adapted to be coupled with a frequency-setting resistor, the method comprising:generating a current through the frequency-setting resistor; coupling the voltage across the frequency-setting resistor to a first input of the integrating amplifier circuit; copying the current to a second input of the integrating amplifier circuit using a controllable current source; generating a ramped output waveform with the integrating amplifier circuit based on the current at the second input of the integrating amplifier circuit; generating discrete changes in the ramped output waveform using a first switched capacitor coupled to the second input of the integrating amplifier circuit, to provide the oscillating waveform with a frequency based on the values of the first switched capacitor and the frequency-setting resistor, the oscillating waveform having a substantially constant average value at a particular frequency; and controlling the coupling of the switched capacitor with the integrating amplifier circuit using switches substantially controlled by the oscillating waveform.