Patent ID: 6930520
Filing Date: 2005-08-16
Classification: H03K

Abstract:
1. A high bandwidth feed-forward oscillator for generating a sawtooth waveform at a prescribed frequency, said sawtooth waveform undergoing successive excursions between respective ones of a set of peak and valley portions Vpeak and Vvalley, comprising: an input port to which a variable input voltage Vin is coupled; an output port from which said sawtooth waveform is derived; a network coupled to said input port and being configured to output said peak voltage value Vpeak for said sawtooth output voltage in proportion to a difference between said input voltage Vin and said valley voltage Vvalley; an amplifier having a first input port coupled to said network and a second input port coupled to receive a voltage value corresponding to said valley voltage value Vvalley for said sawtooth output voltage; a current mirror circuit which is coupled to be driven by said amplifier and is operative to produce a current I in proportion to the voltage difference (Vin−Vvalley); a capacitor coupled to said output port and being alternately charged and discharged by said current I; and a switching circuit which is operative to supply said current I to said capacitor and thereby charge said capacitor until the voltage across said capacitor reaches said peak voltage value Vpeak, and thereafter sink said current I from said capacitor and thereby discharge said capacitor until the voltage across said capacitor reaches said valley voltage value Vvalley.