United States Patent
US Patent 7084705: Automatic biasing of a power device for linear…
US 7084705 · granted 2006-08-01
Abstract
A power device(s) is biased and operates in Class-AB. Crossover distortion is minimized over a broad range of operating conditions, not only for a nominal case. The bias current of a power transistor is automatically adjusted in response to process and temperature variations. Preferably, the adjustment is performed using an error-feedback arrangement. An exemplary `rule` for bias adjustment involves satisfying a proportionality relationship between the small-signal device transconductance at the operating point, and a maximum device transconductance. A dual replica master-slave control architecture is utilized. A self-adapting circuit is provided to change the bias current (or voltage) so that the value is always the optimum value, irrespective of operating temperature and/or process variations. Self-biasing is introduced wherein no manual adjustment is necessary. A stable amplifier is formed having great robustness to process and temperature variations.
| Patent Number | 7084705 |
|---|---|
| Title | Automatic biasing of a power device for linear operation |
| Filed | 2004-06-01 |
| Granted | 2006-08-01 |
| Inventor(s) | Prodanov; Vladimir |
| Assignee | Agere Systems Inc. |
| CPC Classification | H03G 3/10 |
| Number of Claims | 50 |
Abstract
A power device(s) is biased and operates in Class-AB. Crossover distortion is minimized over a broad range of operating conditions, not only for a nominal case. The bias current of a power transistor is automatically adjusted in response to process and temperature variations. Preferably, the adjustment is performed using an error-feedback arrangement. An exemplary `rule` for bias adjustment involves satisfying a proportionality relationship between the small-signal device transconductance at the operating point, and a maximum device transconductance. A dual replica master-slave control architecture is utilized. A self-adapting circuit is provided to change the bias current (or voltage) so that the value is always the optimum value, irrespective of operating temperature and/or process variations. Self-biasing is introduced wherein no manual adjustment is necessary. A stable amplifier is formed having great robustness to process and temperature variations.
Claim 1
A system for biasing an electronic circuit containing a non-linear device, comprising: an electronic circuit containing a non-linear device, said electronic circuit beingoperative to produce an output analog signal from an input analog signal; a sensing circuit coupled to said electronic circuit, said sensing circuit being operative to produce a first signal proportional to a first transconductance value of saidnon-linear device, and a second signal proportional to a second transconductance value of said non-linear device; a comparator circuit coupled to said sensing circuit, said comparator circuit being operative to produce an error signal based on saidfirst signal and said second signal; a control circuit coupled to said comparator circuit, said control circuit being operative to adjust said second transconductance value of said non-linear device using said error signal to provide a feed-back signalto said electronic circuit.
Claims
50 totalA system for biasing an electronic circuit containing a non-linear device, comprising: an electronic circuit containing a non-linear device, said electronic circuit beingoperative to produce an output analog signal from an input analog signal; a sensing circuit coupled to said electronic circuit, said sensing circuit being operative to produce a first signal proportional to a first transconductance value of saidnon-linear device, and a second signal proportional to a second transconductance value of said non-linear device; a comparator circuit coupled to said sensing circuit, said comparator circuit being operative to produce an error signal based on saidfirst signal and said second signal; a control circuit coupled to said comparator circuit, said control circuit being operative to adjust said second transconductance value of said non-linear device using said error signal to provide a feed-back signalto said electronic circuit.