Bias system and method

• US 7,064,607 B2
• Filed: 12/29/2003
• Issued: 06/20/2006
• Est. Priority Date: 12/29/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Rajasekhar, Suribhotla Venkata, Corsi, Marco, Baldwin, David John, Maclean, Kenneth George, Hagan, Tobin
• Primary Examiner(s): NGUYEN, PATRICIA T
• Application Number:
  US10/748,986
• Publication Number:
  US 20050140437A1
• Time in Patent Office: 904 Days
• Field of Search: 330/136, 330/255, 330/261
• US Class Current: 330/136
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 1/3217 in single ended push-pull amplifiers
• CPC Class Codes: H03F 3/3022 CMOS common source output SEPP amplifiers H03F3/3008 takes precedence

Abstract

A bias device that modifies the bias of a device based on an input signal to the device. The device may have a fixed bias, and the bias device can be connected in parallel with the fixed bias. The device can be an amplifier, such as a linear amplifier or a class AB amplifier. The bias device can be configured to provide maximum bias during the device'"'"'s crossover time period.

Claims

1. A system, comprising:

a device that provides an output signal based on an input signal, the device having an associated bias; and

a bias device that provides a boost to the bias of the device based on the input signal;

wherein the bias device is further configured to provide maximum bias during the device'"'"'s crossover time period.

2. The system of claim 1, further comprising a fixed biased device associated with the device, the bias device is connected in parallel to the fixed bias device.

3. The system of claim 1, the device is an amplifier.

4. The system of claim 3, the amplifier is a class AB amplifier.

5. The system of claim 1, the bias device modifies a bias current associated with the device.

8. The system of claim 1, the bias device comprises a full-wave rectifier that provides a full-wave rectified current signal.

9. The system of claim 8, the bias device further comprises a phase shifter, the full-wave rectified current signal is phase shifted based on the input signal.

10. The system of claim 1, the bias device turning off during an absence of the input signal, and turning on during the presence of an input signal.

6. A system, comprising:

a device that provides an output signal based on an input signal, the device having an associated bias; and

a bias device that provides a boost to the bias of the device based on the input signal;

the bias device is further configured to provide maximum bias during the device'"'"'s crossover time period;

wherein, the bias device further comprising a phase shifter that phase shifts the bias based on the input signal.

7. The system of claim 6, the phase shifter phase shifts the boost substantially ninety degrees from the input signal.

11. A system comprising:

means for providing a boost to a bias signal to a biased circuit; and

means for controlling the means for providing a boost, based on an input signal;

further comprising means for phase shifting the bias signal based on the input signal, the means for phase shifting configured to produce a maximum bias at a zero amplitude region.

12. The system of claim 11, further comprising means for providing a fixed bias associated with the biased circuit, the means for providing a fixed bias being in parallel with the means for producing a bias signal.

13. The system of claim 11, the means for controlling further comprising means for turning off the means for providing a boost in the absence of an input signal and for turning on the means for providing a boost in the presence of an input signal.

14. A method, comprising:

monitoring an input signal; and

modifying an amplifier bias based on the monitored input signal to provide a boost at a predetermined time;

further comprising phase shifting the amplifier bias based on the signal being amplified.

15. The method of claim 14, further comprising amplifying the input signal employing the modified bias.

16. The method of claim 14, the modifying further comprising enabling a boost in the presence of an input signal and discontinuing the boost after no input signal has been detected.

17. The method of claim 15, further comprising providing the maximum boost during the amplifier'"'"'s crossover period.