Daniel C Allen

US Patent:

7167119, Jan 23, 2007

Filed:

Dec 20, 2005

Appl. No.:

11/312882

Inventors:

Gong Tom Lei - Austin TX, US
Thuan Luong Nguyen - Austin TX, US
Daniel John Allen - Austin TX, US
John Laurence Melanson - Austin TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03M 3/00

US Classification:

341143, 341150, 341172

Abstract:

A method of sampling an input signal in a delta-sigma modulator having at least an integrator stage and a feedback digital-to-analog converter (DAC) stage includes sampling an input signal at a sampling rate by alternately utilizing the two sampling capacitors during two sampling cycles such that the two sampling capacitors are each being utilized at half the rate of the sampling rate. Samples from the two sampling capacitors are summed at the sampling rate at an intermediate node with a feedback samples provided by the feedback DAC stage at the sampling rate to generate output samples which are output from integrator stage at the sampling rate.

US Patent:

7808324, Oct 5, 2010

Filed:

Mar 17, 2009

Appl. No.:

12/405485

Inventors:

Scott Allan Woodford - Austin TX, US
Daniel John Allen - Austin TX, US
Eric J. Swanson - Buda TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03F 3/04

US Classification:

330297, 330296

Abstract:

A charge pump power supply for an audio power amplifier integrated circuit has an operating mode selected according to an indication of operating environment and/or a process position of the integrated circuit. The operating mode selects the output voltage provided by the charge pump and may also select efficiency by selecting a frequency of operation of the charge pump and/or the effective size of a switching transistor bank. The selection is made in conformity with an indication of a process position of the integrated circuit and/or an indication of an environment of the integrated circuit, such as temperature, power supply voltage and/or load impedance values, and generally also in conformity with a volume (gain) setting, or a detected signal level, so that internal power consumption of the amplifier and charge pump is reduced when a high signal level is not being reproduced at the audio power stage.

US Patent:

7830209, Nov 9, 2010

Filed:

Jan 19, 2009

Appl. No.:

12/355839

Inventors:

Scott Allan Woodford - Austin TX, US
Daniel John Allen - Austin TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03F 3/04

US Classification:

330297, 330279

Abstract:

A charge pump power supply for a consumer device audio power stage has an efficiency selected according to signal level. The frequency of operation of the charge pump and/or the effective size of a switching transistor bank is adjusted based upon a volume (gain) setting, or a detected signal level, so that internal power consumption of the charge pump is reduced when high output current is not required from the audio power stage and consequently from the charge pump. Operating modes of the charge pump are selected by the signal level indication and include at least a high power and a high efficiency mode selected by setting the charge pump operating frequency and/or enabling or disabling switching of one or more of multiple parallel transistors used to implement each switching element of the charge pump, thereby setting the level of gate capacitance being charged/discharged by the gate driver circuit(s).

US Patent:

8008975, Aug 30, 2011

Filed:

Mar 31, 2009

Appl. No.:

12/415788

Inventors:

Daniel J. Allen - Austin TX, US
Eric J. Swanson - Buda TX, US
Scott A. Woodford - Austin TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03F 3/04

US Classification:

330297, 330296

Abstract:

In at least one embodiment, an electronic system includes an amplifier having an on-chip charge pump to provide a gate boost voltage to boost a gate voltage of at least one on-chip field effect transistor (FET) of an output stage of an amplifier. In at least one embodiment, the gate boost voltage boosts the gate voltage higher than the supply voltage rail to increase an overdrive voltage of the on-chip FET. In at least one embodiment, the gate boost voltage boosts the DC bias of an input signal and, thus, generation of gate boost voltage by the on-chip charge pump is signal-independent, i. e. independent of the input signal. Increasing the overdrive voltage increases the efficiency of the amplifier by decreasing the difference between the maximum swing of the output voltage and the voltage supply rails of the at least one on-chip FET relative to conventional designs.

US Patent:

8311243, Nov 13, 2012

Filed:

Dec 13, 2006

Appl. No.:

11/610496

Inventors:

John Christopher Tucker - Austin TX, US
Daniel John Allen - Austin TX, US
John L. Melanson - Austin TX, US
Ammisetti Prasad - Austin TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03F 99/00

US Classification:

381120, 381121, 330297, 330 10, 330146, 330202

Abstract:

An energy-efficient consumer device audio power output stage provides improved battery life and reduced power dissipation. A power supply having a selectable operating mode supplies the power supply rails to the power amplified output stage. The operating mode is controlled in conformity with the audio signal level, which may be determined from a volume control setting of the device and/or from a signal level detector that determines the amplitude of the signal being amplified. The power supply may be a charge pump in which the operating mode uses a capacitive divider to provide for selection of a power supply output voltage that is a rational fraction of the power supply output voltage in a full-voltage operating mode.

US Patent:

8390493, Mar 5, 2013

Filed:

Jun 30, 2010

Appl. No.:

12/827468

Inventors:

Harish Raghavan - Austin TX, US
John Christopher Tucker - Austin TX, US
Scott Allan Woodford - Austin TX, US
Daniel John Allen - Austin TX, US
Anand Ilango - Austin TX, US

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

H03M 1/00

US Classification:

341142, 324 95

Abstract:

A voltage reference circuit provides a precision voltage reference output without requiring a filter capacitor. The voltage reference output is generated by a digitally-controlled source, which has a value set by the output of a digital filter that filters the output of a comparison circuit that compares the voltage reference output to another reference. A selectable mode can be provided to provide a fast response during a startup/reset period and an optional hold or narrowband response after startup. The mode selection may also offer selection of an externally-supplied digital control value and/or a resistor divider type voltage reference as an alternative to the digitally-controlled source.

US Patent:

20140050330, Feb 20, 2014

Filed:

Aug 17, 2012

Appl. No.:

13/588021

Inventors:

Daniel John Allen - Austin TX, US
Thuan Luong Nguyen - Austin TX, US
Anand S. Ilango - Austin TX, US
John Christopher Tucker - Austin TX, US

International Classification:

H04R 1/10

US Classification:

381 74

Abstract:

A circuit including headset type detection provides compatibility with different transducer types, such as headphones provided by different manufacturers. An audio circuit that generates or receives an audio signal includes electrical terminals for coupling to a transducer device, at least one of which carries the audio signal. A transducer device type detection circuit is included and detects a type of a transducer device coupled to the audio device from characteristics measured at the multiple electrical terminals when the transducer is coupled to the audio device. The circuit also includes a configuration control circuit for altering a configuration of the audio device according to a detected type of the transducer device.

US Patent:

20190058484, Feb 21, 2019

Filed:

Oct 23, 2018

Appl. No.:

16/168067

Inventors:

- Edinburgh, GB
Daniel J. ALLEN - Austin TX, US
John L. MELANSON - Austin TX, US
Aniruddha SATOSKAR - Round Rock TX, US
Akshay GODBOLE - Austin TX, US

Assignee:

Cirrus Logic International Semiconductor Ltd. - Edinburgh

International Classification:

H03M 1/18
H04R 3/04
H03H 19/00

Abstract:

A system may comprise a high-pass filter having an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a switched-capacitor resistor coupled between the output and a reference voltage, and control circuitry configured to control the reference voltage to cancel current leakage into a circuit coupled to the output. The input, the output, the capacitor, and the switched-capacitor resistor may be arranged to generate the output signal as a high-pass filtered version of the input signal and the high-pass filter may be configured to operate in a plurality of modes comprising at least a high-impedance mode and a low-impedance mode in which the resistance of the switched-capacitor resistor is significantly smaller than the resistance when in the high-impedance mode.A system may include a plurality of processing paths having a first path configured to generate a first digital signal based on an analog input signal and a second path configured to generate a second digital signal based on the analog input signal, the second path having a high-pass filter for filtering the analog input signal prior to the analog input signal being processed by the remainder of the second path, and the high-pass filter having a corner frequency. Control circuitry may be configured to determine frequency-dependent weighted proportions of the first and second digital signals to be combined into an output digital signal based on a characteristic of the analog input signal. Frequency-dependent weighted proportions may be such that the digital output signal includes spectral content of the first digital signal below the corner frequency to account for spectral content of the second digital signal below the corner frequency being filtered.A system may include an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a variable resistor coupled to the output and having a plurality of modes including a first mode in which the variable resistor has a first resistance and a second mode in which the variable resistor has a second resistance, and control circuitry configured to determine a difference between the input signal and the output signal and switch between modes of the plurality of modes when the difference is less than a predetermined threshold.