GB2488455B - DC offset compensation - Google Patents

DC offset compensation

Info

Publication number
GB2488455B
GB2488455B GB201207051A GB201207051A GB2488455B GB 2488455 B GB2488455 B GB 2488455B GB 201207051 A GB201207051 A GB 201207051A GB 201207051 A GB201207051 A GB 201207051A GB 2488455 B GB2488455 B GB 2488455B
Authority
GB
United Kingdom
Prior art keywords
output signal
offset
vco
compensation
counter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
GB201207051A
Other versions
GB2488455A (en
GB201207051D0 (en
Inventor
John Paul Lesso
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cirrus Logic International UK Ltd
Original Assignee
Wolfson Microelectronics PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wolfson Microelectronics PLC filed Critical Wolfson Microelectronics PLC
Priority to GB201207051A priority Critical patent/GB2488455B/en
Publication of GB201207051D0 publication Critical patent/GB201207051D0/en
Publication of GB2488455A publication Critical patent/GB2488455A/en
Application granted granted Critical
Publication of GB2488455B publication Critical patent/GB2488455B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/181—Low-frequency amplifiers, e.g. audio preamplifiers
    • H03F3/183—Low-frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
    • H03F1/305—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in case of switching on or off of a power supply
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
    • H03G3/348—Muting in response to a mechanical action or to power supply variations, e.g. during tuning; Click removal circuits
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/03—Indexing scheme relating to amplifiers the amplifier being designed for audio applications
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/375—Circuitry to compensate the offset being present in an amplifier

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Multimedia (AREA)
  • Amplifiers (AREA)

Abstract

In an audio amplifier, a DC offset compensation circuit is provided in which an offset compensating feedback path (107) comprises at least one voltage controlled oscillator (VCO) (108) and a counter (109). The VCO (108) provides, over time, a first VCO output signal based on the amplified output signal (Sout) and a second VCO output signal based on a reference signal (VREF). The counter (109) generates first pulse counts based upon the first VCO output signal and second pulse counts based upon the second VCO output signal and provides a compensation signal based on a comparison of the first and second pulse counts. The output signal of the counter (109) may be fed back via a DAC (112) or via digital paths (dotted). The low area occupied by the compensation circuit reduces the need to multiplex offset compensation across a large number of audio paths. In the present invention, the compensation circuitry is multiplexed between a first feedback loop for compensating offset in a first part of a signal path, and a second loop for compensating for offset in a second part of the signal path.
GB201207051A 2010-12-16 2010-12-16 DC offset compensation Active GB2488455B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB201207051A GB2488455B (en) 2010-12-16 2010-12-16 DC offset compensation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB201207051A GB2488455B (en) 2010-12-16 2010-12-16 DC offset compensation

Publications (3)

Publication Number Publication Date
GB201207051D0 GB201207051D0 (en) 2012-06-06
GB2488455A GB2488455A (en) 2012-08-29
GB2488455B true GB2488455B (en) 2013-08-07

Family

ID=46261688

Family Applications (1)

Application Number Title Priority Date Filing Date
GB201207051A Active GB2488455B (en) 2010-12-16 2010-12-16 DC offset compensation

Country Status (1)

Country Link
GB (1) GB2488455B (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5397944A (en) * 1993-04-09 1995-03-14 Crystal Semiconductor Corporation Dense offset calibration circuitry and method
WO2007080528A1 (en) * 2006-01-09 2007-07-19 Nxp B.V. Single-ended amplifier
GB2459865A (en) * 2008-05-07 2009-11-11 Wolfson Microelectronics Plc Audio amplifier with dc offset compensation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5397944A (en) * 1993-04-09 1995-03-14 Crystal Semiconductor Corporation Dense offset calibration circuitry and method
WO2007080528A1 (en) * 2006-01-09 2007-07-19 Nxp B.V. Single-ended amplifier
GB2459865A (en) * 2008-05-07 2009-11-11 Wolfson Microelectronics Plc Audio amplifier with dc offset compensation

Also Published As

Publication number Publication date
GB2488455A (en) 2012-08-29
GB201207051D0 (en) 2012-06-06

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732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)

Free format text: REGISTERED BETWEEN 20150820 AND 20150826