Monotonic and voltage supply independent automatic gain control amplifier

• US 20080094138A1
• Filed: 10/18/2006
• Published: 04/24/2008
• Est. Priority Date: 10/18/2006
• Status: Active Grant

• Current Assignee: Sige Semiconductor Europe Ltd (Skyworks Solutions Incorporated)
• Original Assignee: Sige Semiconductor Europe Ltd (Skyworks Solutions Incorporated)
• Inventors: Fulga, Stefan
• Granted Patent: US 7,893,761 B2
• Time in Patent Office: Days
• US Class Current: 330/140
• CPC Class Codes: H03G 3/001 Digital control of analog signals
• CPC Class Codes: H03G 3/007 Control dependent on the supply voltage
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals

Abstract

A method and circuit are provided wherein the magnitude of an RF signal provided by RF circuit is used to derive a control set point of the RF circuit via an intermediate controller circuit. This controller circuit having the specific function of providing the actual voltage applied to the control point of the RF circuit, via the use of a charge pump, regulator or combination thereof. In this manner the controller limits the maximum applicable voltage set by the limiting characteristics of the charge pump, voltage regulator, or combination thereof. Such limiting characteristics allow the control of the RF circuit to be stabilized against a variety of external factors such as ambient temperature, battery voltage, circuit aging, amongst other factors in a manner exploiting a minimum of additional electronics thereby providing for such performance enhancements with minimum additional die footprint and power consumption.

Claims

1. A method for providing monotonic amplification of an RF signal comprising:

providing an RF input signal;

amplifying with an amplifier the RF input signal to provide an RF output signal;

measuring an amplitude of the RF output signal to provide an amplitude measurement; and

,

adjusting a control signal provided to the amplifier in response to one of said amplitude measurement and a supply voltage applied to the amplifier, the control signal regulated such that over a range of amplification, the first derivative of the gain of the amplifier as a function of the control signal is positive and constrained between a value at a first endpoint of the range and a value at a second other endpoint of the range.

2. An amplifier according to claim 1 wherein amplifier maintains a gain absent a point having the first differential of gain being zero.

3. A method according to claim 1 wherein the control signal comprises a bias control voltage signal.

4. A method according to claim 1 wherein regulating the control signal is performed by a circuit comprising a charge pump.

5. A method according to claim 1 wherein regulating the control signal is performed by a circuit comprising a voltage regulator.

6. A method according to claim 1 wherein controlling the control signal is performed by a circuit comprising both a charge pump and a voltage regulator disposed in series between the amplifier and the supply voltage.

7. A method according to claim 1 such that monotonic gain profile is independent of at least one of temperature, circuit age, and degradation of a battery supply voltage.

8. A circuit comprising:

an input port for receiving a variable RF signal for amplification;

an output port for providing an amplified version of the variable RF signal therefrom;

an amplifier circuit disposed electrically between the input port and the output port for providing gain to the variable RF signal, the amplifier including a control voltage input port for receiving a control voltage signal and a voltage supply port for receiving a supply voltage signal, and,

a detector for detecting an amplitude of the amplified variable RF signal and for providing a control voltage signal therefrom to the input port of a feedback circuit, the feedback circuit comprising a regulator for regulating the control voltage signal.

9. A circuit according to claim 8 wherein the circuit maintains the first derivative of the gain of the amplifier as a function of the control voltage as both positive and constrained.

10. A circuit according to claim 8 wherein the control voltage signal comprises a bias control voltage of the amplifier.

11. A circuit according to claim 8 wherein the regulator providing voltage regulation of the control voltage signal comprises a charge pump.

12. A circuit according to claim 8 wherein the supply voltage signal is regulated by a supply regulator which comprises a charge pump.

13. A circuit according to claim 8 wherein the regulator providing voltage regulation of the control signal comprises a voltage regulator.

14. A circuit according to claim 8 wherein the regulator providing voltage regulation of the supply voltage signal comprises a voltage regulator.

15. A circuit according to claim 8 wherein the maximum value of the control voltage signal is approximately that voltage for which the gain of the amplifier is a maximum.

16. A circuit according to claim 8 wherein the maximum value of the control voltage signal is approximately that for which the first derivative of the gain of the amplifier as a function of the control voltage signal is positive, constrained, and asymptotically zero.

17. A circuit according to claim 8 wherein the amplifier provides approximately maximum amplified RF input signal for a received signal while maintaining operation of the amplifier between a first gain value and a second other gain value, the first gain value and the second other gain value defining the range of operation of the amplifier.

18. A circuit according to claim 8 wherein the amplifier is an automatic gain control amplifier.

19. A circuit according to claim 8 wherein the amplifier comprises a plurality of amplifiers disposed in series one with another, the plurality of amplifiers having an electrical filter disposed there between.

20. A circuit according to claim 8 wherein the amplifier comprises a plurality of amplifier gain stages disposed in parallel, a switching circuit for selecting an amplifier gain stage from the plurality of amplifier gain stages for amplifying of the RF input signal, and wherein the charge pump regulates the control voltage signal applied to the selected amplifier gain stage.

21. A circuit according to claim 8 wherein the detector comprises an analog-to-digital converter.

22. A circuit according to claim 8 such that monotonic gain profile is independent of at least one of temperature, circuit age, and degradation of a battery supply voltage.

23. A storage medium having stored therein data for when executed resulting in a circuit comprising:

an input port for receiving a variable RF signal for amplification;

an output port for providing an amplified version of the variable RF signal therefrom;

an amplifier circuit disposed electrically between the input port and the output port for providing gain to the variable RF signal, the amplifier including a control voltage input port for receiving a control voltage signal, and a voltage supply port for receiving a supply voltage signal, and,

a detector for detecting the amplitude of the amplified version of the variable RF signal and for providing a control voltage signal therefrom to the input port of a feedback circuit, the feedback circuit comprising a regulator for regulating the control voltage signal.

25. A storage medium according to claim 23, wherein the regulator comprises a charge pump.

26. A storage medium according to claim 23, wherein the regulator comprises a charge pump in combination with a voltage regulator.

24. A storage medium having stored therein data for when executed resulting in a controller circuit comprising:

a detector for detecting the amplitude of an RF signal provided by an RF circuit, and providing a proportional signal therefrom;

a means of providing a control voltage signal to the RF circuit via a regulating circuit, wherein said control voltage signal is defined in accordance to the magnitude of the detectors output signal;

and wherein said control voltage signal is used to control the performance of the RF circuit.

27. A storage medium according to claim 24, wherein the regulating circuit comprises a charge pump.

28. A storage medium according to claim 24, wherein the regulating circuit comprises a charge pump in combination with a voltage regulator.