David M Rich

US Patent:

53075170, Apr 26, 1994

Filed:

Oct 17, 1991

Appl. No.:

7/778501

Inventors:

David A. Rich - Woodmere NY

International Classification:

H04B 110

US Classification:

455306

Abstract:

An improved adaptive notch filter for removing undesired cochannel FM interference includes in-phase and quadrature signal processing paths in which the undesired FM signal is translated to zero frequency, i. e. to DC. In each of the in-phase and quadrature phase signal paths, a first multiplier translates the input frequency spectrum in a dynamic manner so that the frequency of the undesired FM signal is always centered on DC. The undesired signal, now at DC, is filtered out by a high pass filter with a sharp rolloff. The output of the high pass filter is remultiplied in a second multiplier to translate the desired FM signal back to the original position in the frequency spectrum. In order to eliminate an unwanted difference frequency remodulation signal at the output of the second multiplier, the quadrature phase signal path performs a parallel operation on the same input signal, but with a quadrature phase (90 degree phase shift) control signal. The output the in-phase and quadrature signal processing circuits are combined in an adder circuit to cancel the unwanted difference frequency remodulation signal.

US Patent:

49375776, Jun 26, 1990

Filed:

Jun 23, 1987

Appl. No.:

7/065939

Inventors:

David Rich - Woodmere NY
Peter Staley - Kings Park NY

Assignee:

Microchip Technology Inc. - Chandler AZ

International Classification:

H03M 302

US Classification:

341143

Abstract:

A feedback coder, which employs simple CMOS push/pull amplifiers as gain elements, along with a bistable circuit, in its preferred embodiment takes the form of a second-order delta-sigma modulator. The output of the modulator is converted into pulse code modulated words by a finite impluse response filter which incorporates a partial coefficient generator utilizing simplified logic. The generator output is provided to an accumulator in which the stage operate at reduced speed. A simple multiplexer generates a serial output. The entire converter can be integrated on a semiconductor chip of relatively small area.

US Patent:

47960043, Jan 3, 1989

Filed:

Feb 14, 1986

Appl. No.:

6/829624

Inventors:

David Rich - Woodmere NY
Peter Staley - Kings Park NY
David Coyne - Fife, GB6

Assignee:

General Instrument Corp. - New York NY

International Classification:

H03M 302

US Classification:

341143

Abstract:

A feedback coder, which employs simple CMOS push/pull amplifiers as gain elements, along with a bistable circuit, in its preferred embodiment takes the form of a second-order delta-sigma modulator. The output of the modulator is converted into pulse code modulated words by a finite impulse response filter which incorporates a partial coefficient generator utilizing simplified logic. The generator output is provided to an accumulator in which the stages operate at reduced speed. A simple multiplexer generates a serial output. The entire converter can be integrated on a semiconductor chip of relatively small area.

US Patent:

48600121, Aug 22, 1989

Filed:

Jun 22, 1987

Appl. No.:

7/065263

Inventors:

David Rich - Woodmere NY
Peter Staley - Kings Park NY

Assignee:

Microchip Technology Incorporated - Chandler AZ

International Classification:

H03M 302

US Classification:

341143

Abstract:

A feedback coder, which employs simple CMOS push/pull amplifiers as gain elements, along with a bistable circuit, in its preferred embodiment takes the form of a second-order delta-sigma modulator. The output of the modulator is converted into pulse code modulated words by a finite impulse response filter which incorporates a partial coefficient generator utilizing simplified logic. The generator output is provided to an accumulator in which the stages operate at reduced speed. A simple multiplexer generates a serial output. The entire converter can be integrated on a semiconductor chip of relatively small area.