Kenneth H Barnett

US Patent:

7598793, Oct 6, 2009

Filed:

Mar 21, 2008

Appl. No.:

12/053388

Inventors:

Susanta Sengupta - Leander TX, US
Kenneth Charles Barnett - Austin TX, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03H 11/40

US Classification:

327524, 327334

Abstract:

A capacitance multiplier circuit is configured to sense a current through a capacitor in an RC filter of the circuit and to multiply the current so as to achieve a capacitance multiplier effect without adding additional circuitry or requiring additional power. The circuit includes an RC filter, a first signal path connected to a filter output, and a second signal path connected to an input to the filter. A current output through the filter (i) is split between the two paths, sensed in the first path and multiplied in the second path. The multiplied current is fed back from the second path to the filter input to raise the effective capacitance of capacitor C. The capacitance multiplier circuit, in raising the effective capacitance of the capacitor in the filter, does not affect the frequency response, linearity performance and/or stability of the overall circuit.

US Patent:

7719352, May 18, 2010

Filed:

Aug 1, 2007

Appl. No.:

11/832581

Inventors:

Tae Wook Kim - Austin TX, US
Kenneth Charles Barnett - Austin TX, US
Harish Muthali - Round Rock TX, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03F 1/14

US Classification:

330 51, 330124 R, 330307, 330295

Abstract:

Active circuits with isolation switches are described. In one design, an apparatus includes first and second amplifiers coupled in parallel. Each amplifier receives an input signal and provides an output signal. Each amplifier has a switch that isolates the amplifier when the amplifier is turned off. The first and second amplifiers may be high and low gain amplifiers or two low noise amplifiers (LNAs). The first and second amplifiers may be for different communication systems, different frequency bands, and/or different gain ranges. In general, any number of amplifiers may be coupled in parallel, and each amplifier may have a switch to isolate that amplifier when turned off. A switch for an amplifier may be a shunt switch coupled between an internal node of the amplifier and ground. The shunt switch may be closed when the amplifier is turned off and may be opened when the amplifier is turned on.

US Patent:

7834698, Nov 16, 2010

Filed:

May 23, 2008

Appl. No.:

12/126189

Inventors:

Susanta Sengupta - Leander TX, US
Kenneth Charles Barnett - Austin TX, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03F 3/45

US Classification:

330261, 330253

Abstract:

According to some embodiments, an amplifier may include a transconductance stage, a tail current source stage, and an adaptive biasing stage. The transconductance stage may be configured to receive an input voltage. The tail current source stage may be configured to provide current to the transconductance stage. The adaptive biasing stage may capacitively couple the transconductance stage to the tail current source stage.

US Patent:

7839202, Nov 23, 2010

Filed:

Oct 2, 2007

Appl. No.:

11/866120

Inventors:

Susanta Sengupta - Leander TX, US
Kenneth Charles Barnett - Austin TX, US
Yunfei Feng - Austin TX, US

Assignee:

QUALCOMM, Incorporated - San Diego CA

International Classification:

G05F 1/10

US Classification:

327539

Abstract:

A bandgap voltage reference circuit and methods for generating a bandgap reference voltage are disclosed. An operational amplifier receives first and second input voltages from a first and second current path, respectively. A buffer stage is coupled to an output of the operational amplifier and generates third and fourth voltages on the first and second path. A temperature dependent current is generated using the third and fourth voltages in combination with a first diode, second diode and a resistor. A third current path mirrors the temperature dependent current and a temperature independent voltage is generated for the bandgap reference voltage in the third current path using the temperature dependent current in combination with a second resistor and related diode.

US Patent:

7888983, Feb 15, 2011

Filed:

Sep 11, 2009

Appl. No.:

12/558278

Inventors:

Kun Zhang - Austin TX, US
Kenneth C. Barnett - Austin TX, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03K 3/017

US Classification:

327175, 327172

Abstract:

Techniques for generating a signal having a predetermined duty cycle. In an exemplary embodiment, a first counter is configured to count a first number of cycles of an oscillator signal, and a second counter is configured to count a second number of cycles of the oscillator signal, with the second number being greater than the first number. The output of the second counter is used to reset the first and second counters, while the outputs of the first and second counters further drive a toggle latch for generating the signal having predetermined duty cycle. Further aspects include techniques for accommodating odd and even values for the second number.

US Patent:

7889007, Feb 15, 2011

Filed:

Apr 5, 2007

Appl. No.:

11/696876

Inventors:

Namsoo Kim - San Diego CA, US
Kenneth Charles Barnett - Austin TX, US
Vladimir Aparin - San Diego CA, US

Assignee:

QUALCOMM, Incorporated - San Diego CA

International Classification:

H03F 3/18

US Classification:

330264, 330277, 330254, 330310

Abstract:

A differential amplifier, which has good linearity and noise performance, includes a first side that includes first, second, third, and fourth transistors and an inductor. The first and second transistors are coupled as a first cascode pair, and the third and fourth transistors are coupled as a second cascode pair. The third transistor has its gate coupled to the source of the second transistor, and the fourth transistor has its drain coupled to the drain of the second transistor. The first transistor provides signal amplification. The second transistor provides load isolation and generates an intermediate signal for the third transistor. The third transistor generates distortion components used to cancel third order distortion component generated by the first transistor. The inductor provides source degeneration for the first transistor and improves distortion cancellation. The sizes of the second and third transistors are selected to reduce gain loss and achieve good linearity for the amplifier.

US Patent:

7902925, Mar 8, 2011

Filed:

Nov 22, 2005

Appl. No.:

11/285949

Inventors:

Namsoo Kim - San Diego CA, US
Kenneth Charles Barnett - Austin TX, US
Vladimir Aparin - San Diego CA, US

Assignee:

QUALCOMM, Incorporated - San Diego CA

International Classification:

H03F 1/22

US Classification:

330311, 330283

Abstract:

An amplifier, which has good linearity and noise performance, includes first, second, third, and fourth transistors and an inductor. The first and second transistors are coupled as a first cascode pair, and the third and fourth transistors are coupled as a second cascode pair. The third transistor has its gate coupled to the source of the second transistor, and the fourth transistor has its drain coupled to the drain of the second transistor. The first transistor provides signal amplification. The second transistor provides load isolation and generates an intermediate signal for the third transistor. The third transistor generates distortion components used to cancel third order distortion component generated by the first transistor. The inductor provides source degeneration for the first transistor and improves distortion cancellation. The sizes of the second and third transistors are selected to reduce gain loss and achieve good linearity for the amplifier.

US Patent:

7949322, May 24, 2011

Filed:

Mar 9, 2007

Appl. No.:

11/684120

Inventors:

Tae Wook Kim - Austin TX, US
Kenneth Charles Barnett - Austin TX, US

Assignee:

QUALCOMM, Incorporated - San Diego CA

International Classification:

H04B 1/06
H04B 1/16
H03F 3/52

US Classification:

4552481, 4551942, 330105, 330282

Abstract:

This disclosure is directed to a frequency-selective low noise amplifier (LNA) with wide-band impedance and noise matching. The LNAS may include a closed loop circuit that supports wideband input matching. For example, the closed loop circuit may be configure to impedance match an input signal and provide a low noise figure. In addition, the LNA may include an open loop circuit that amplifies the input signal and provides a high output impedance. The open loop circuit may further include a selectivity filter that filters out frequencies outside a desired frequency band. The LNA may drive a tunable band-pass filter via the open loop circuit.