Thomas K Ha

US Patent:

6420929, Jul 16, 2002

Filed:

Aug 23, 2001

Appl. No.:

09/682348

Inventors:

Thomas Ha - Huntington Beach CA 92648

International Classification:

H03F 100

US Classification:

330151

Abstract:

An N way carrier cancellation coupler ( ), N being greater than 1, for use in a feed forward power amplifier ( ), comprising a first N way divider ( ), a second N way divider ( ), an N way combiner ( ), N carrier cancellation couplers ( ), the inputs of each of the N carrier cancellation couplers ( ) connected to the first N way divider ( ) and the second N way divider ( ), and the output of each of the N carrier cancellation couplers connected to the N way combiner ( ). An M way distortion cancellation coupler ( ) is also provided, as well as a feed forward power amplifier comprising a feed forward power amplifier having a first loop and a second loop, an N way carrier cancellation coupler ( ), or an M way distortion cancellation coupler ( ), or both.

US Patent:

6493543, Dec 10, 2002

Filed:

Oct 19, 1998

Appl. No.:

09/174705

Inventors:

Do B. Shin - Laguna Hills CA
Thomas Ha - Huntington Beach CA

Assignee:

Powerwave Technologies, Inc. - Irvine CA

International Classification:

H03F 126

US Classification:

455126, 330149, 330151, 327359

Abstract:

An apparatus and method reduce out-of-band frequency components of an amplified, multichannel RF signal able to have at least two frequency bandwidth limited signal channels, each channel having a respective carrier frequency which is not known in advance. The channels can, for example, be dedicated to CDMA signals. Each channel of the amplified RF signal has both in-band frequency components and out-of-band frequency components. The apparatus and method feature a network for amplifying an input signal for producing the amplified RF signal, the network having adjustable electrical characteristics, and a control system connected to the network for locating a frequency within the bandwidth of one of the channels of the amplified RF signal and for detecting energy in the out-of-band frequency components for the one located channel for producing control signals relating to the energy in that one channel. As a result of adjusting the electrical characteristics of the network, the energy in the out-of-band frequency components for that channel, and all other channels of interest, can be reduced.

US Patent:

6700442, Mar 2, 2004

Filed:

Mar 1, 2002

Appl. No.:

09/683918

Inventors:

Thomas Quang Ha - Huntington Beach CA 92648

International Classification:

H03F 368

US Classification:

330124R, 330149

Abstract:

A low distortion power amplifier, where N is greater than 1, comprising an input divider ( ) for dividing a received input signal ( ), and outputting a first signal ( ) and a main signal ( ), a carrier cancellation component ( ) connected to the input divider ( ) for receiving the first signal ( ) and outputting a distortion signal ( ), an input attenuator ( ) receiving the main signal ( ) and outputting an attenuated main signal ( ) to an input delay device ( ) yielding a delayed, attenuated main signal ( ), and an N way distortion cancellation component ( ) having a first input connected to the carrier cancellation component ( ) for receiving the distortion signal ( ) and a second input connected to the input delay device ( ) for receiving the delayed, attenuated main signal ( ) and an output for outputting an amplified output signal ( ) having low distortion.

US Patent:

53231198, Jun 21, 1994

Filed:

Jul 14, 1991

Appl. No.:

7/690927

Inventors:

Jack Powell - Cestas, FR
Thomas Ha - Gardena CA
Georg Luettgenau - Madrid, ES

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H03F 126

US Classification:

330151

Abstract:

The present invention provides an amplifier arrangement to which feed forward correction is applied by a comparison loop including comparison means for comparing amplifier input with amplifier output to provide an error signal, a cancellation loop including secondary amplifier means for amplifying the error signal and combining means for combining said amplified signal with said amplifier output, a pilot generator coupled to said amplifier input to introduce a pilot tone therein, detector means for detecting a level of pilot tone in said amplifier output and correction means for correcting said cancellation loop performance as a function of said detection wherein said pilot generator is further coupled to a multiplier receiving said amplifier output, said multiplier producing an output signal arranged to control a loop parameter to effect said correction. The distortion performance of a feed forward amplifier is thereby improved, alternatively an amplifier of inferior distortion performance, but potentially higher efficiency may be used.

US Patent:

51573466, Oct 20, 1992

Filed:

Jun 19, 1991

Appl. No.:

7/690930

Inventors:

Jack Powell - Cestas, FR
Thomas Ha - Gardena CA

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H03F 132

US Classification:

330151

Abstract:

A r. f. wideband high power amplifier (1) receives an input signal at its input via a coupler (7) whenever a signal for amplification is applied to an input port (15). The output of the amplifier (1) is tapped by a coupler (8) and fed to an input of a comparator (3). The input signal applied at the input port (15) is fed to a second input of the comparator (3) via a delay line (5), arranged to introduce a delay substantially equal to that of the power amplifier (1). The comparator (3) produces at its output an error signal representative of the difference between the input signal fed via the amplified and the delayed path. A combiner (16) serves to introduce the amplified error signal to the amplifier output signal such that the error signal is in anti-phase therewith. Thus, the resultant signal produced at an output port (4) has had feed forward distortion cancellation. In accordance with the present invention the arrangement further includes an amplitude compensating network (8) in the form of a PIN-diode attenuator, controlled by a signal from a comparator (14).