Patent Number: 6,297,693

Title: Techniques for synchronizing a self oscillating variable frequency modulator to an external clock

Abstract: The frequency spectrum of variable frequency class D modulator interferes with RF signals in the AM bandwidth. Here several techniques solve the problem including an amplifier that synchronizes an external clock input the summing node of the integrator, an amplifier that gates an external clock to the modulator using a transmission gate that responds to the AM frequency, and an amplifier that adjusts its own hysteresis to provide a clock that does not interfere with AM input signals.

Inventors: Pullen; Stuart W. (Raleigh, NC)

Assignee: Red Chip Company Limited

International Classification: H03C 1/06 (20060101); H03F 3/20 (20060101); H03F 3/217 (20060101); H03F 1/32 (20060101); H03C 1/00 (20060101); H03F 003/38 ()

Expiration Date: 10/02/2018