Wai Ling Lee

57240370, Mar 3, 1998

May 23, 1995

8/447735

Wai L. Lee - Wilmington MA

Analog Devices, Inc. - Norwood MA

H03M 300

341143

A computed tomography imaging method includes receiving an analog beam intensity signal from a computed tomography scanner and converting the signal into a series of digital representations of the signal at successive points in time using a predetermined sample rate. Indications that a portion of the scanner has reached a certain position relative to the beam are received asynchronously with respect to the sample rate. The value of at least one of the digital representations is adjusted in response to the indications to obtain a corrected digital representation of the analog signal.

57320020, Mar 24, 1998

May 23, 1995

8/447746

Wai L. Lee - Wilmington MA
Tom W. Kwan - Milpitas CA

Analog Devices, Inc. - Norwood MA

G06F 1717
G06F 1710

3647241

A digital filtering method that includes sampling an input signal at a first rate, integrating the signal, sampling the integrated version at a different rate, and combining the sampled integrated version with the input signal. The method can include again integrating the integrated version, sampling the twice integrated version at a third rate different from the first and second rates, and combining the twice integrated version with the integrated version and the input signal. The integrated version can be again integrated, the twice integrated version can be sampled at a third rate different from the first and second rates, and the twice integrated version can be combined with the integrated version. A common circuit component can be multiplexed to participate in two integrating steps.

57397201, Apr 14, 1998

Mar 11, 1997

8/815336

Wai L. Lee - Wilmington MA

Analog Devices, Inc. - Norwood MA

H03F 114

330 9

A switched-capacitor circuit that includes a first signal path disposed between a first input node and a first output node, and a second signal path disposed between a second input node and a second output node. The first and second switches can be alternately disposed within the first and second signal paths. An amplifier responsive to the switches can be provided, and its offset can be cancelled. The outputs of the amplifiers can be maintained, and this can involve buffering.

56213450, Apr 15, 1997

Apr 7, 1995

8/418546

Wai L. Lee - Wilmington MA
Norman D. Grant - Windham NH
Paul F. Ferguson - Dracut MA

Analog Devices, Inc. - Norwood MA

H03C 300
H03H 1116

327254

A circuit that provides samples of in-phase and quadrature components of an input waveform includes an oversampling ADC that receives the input waveform and converts the input waveform to digital samples at an oversampling rate. A first digital filter, coupled to the ADC, receives the digital samples from the ADC and provides the in-phase component samples of the input waveform. A second digital filter, coupled to the ADC, receives the digital samples from the ADC and provides the quadrature component samples of the input waveform.

54952000, Feb 27, 1996

Apr 6, 1993

8/043402

Tom W. Kwan - Reading MA
Paul F. Ferguson - Dracut MA
Wai L. Lee - Wilmington MA

Analog Devices, Inc. - Norwood MA

H03B 100

327554

A biquad switched capacitor filter is preferably utilized as the output filter in a sigma delta digital-to-analog converter. The switched capacitor filter uses a cross-coupled switched capacitor circuit which delivers charge to the capacitors on both phases of the clock. As a result, the sizes of the capacitors can be reduced by a factor of two, while delivering the same charge as a single sampling circuit. By using the cross-coupled switching circuit everywhere in the filter, the sensitivity to capacitor mismatches is substantially reduced. The clock phases applied to the stages of the filter are alternated so that there is a one clock cycle delay around each loop containing two filter stages, thereby insuring the stability of the filter.