Dynamic bias for RF power amplifiers

• US 20010041547A1
• Filed: 02/01/2001
• Published: 11/15/2001
• Est. Priority Date: 03/29/2000
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Kazakevich, Leonid, Cabrol, Patrick
• Granted Patent: US 6,684,064 B2
• Time in Patent Office: Days
• US Class Current: 455/127.1
• CPC Class Codes: H03F 1/02 Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/0233 by using a signal derived from the output signal, e.g. bootstrapping the voltage supply
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 1/0266 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/474 A current mirror being used as sensor
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3084 in receivers or transmitters for electromagnetic waves other than radiowaves, e.g. lightwaves H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control
• CPC Class Codes: H04B 2001/045 with means for improving efficiency
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A system and method for dynamically adjusting the operating bias of an RF transmitter amplifier in response to a power control signal. The invention provides high-efficiency RF power amplification for applications where the available power source is limited. The invention uses a power control signal resident in wireless communication system architectures with a detector and voltage to current converter to arrive at a dynamic amplifier operating bias.

Claims

1. A system for dynamically biasing an RF power amplifier which amplifies a communication signal, having a first signal input for receiving the communication signal, a signal output and a bias input;

the system comprising;

a detector, for receiving said communication signal and removing modulation components from said communication signal to provide a detector output signal;

a second signal input for providing a TPC signal;

a converter, coupled to said detector and said second signal input, said converter for processing said TPC signal and said detector output signal to generate a current signal; and

a current mirror for receiving said current signal and feedback from said signal output and for comparing said current signal with said feedback to produce a bias signal;

whereby said bias input receives said bias signal and dynamically adjusts the bias point of said amplifier.

2. The system of

claim 1

, whereby said converter performs said processing by weighting both said TPC signal and said detector output signal and then combining said TPC and detector output signals.

3. The system of

claim 1

, whereby said current mirror further scales said current signal and said feedback signal prior to said comparison.

4. The system of

claim 2

, whereby said current mirror further scales said current signal and said feedback signal prior to said comparison.

5. The system of

claim 1

, whereby said communication signal is a CDMA signal.

6. A method for dynamically biasing an RF power amplifier which amplifies a communication signal, having a first signal input for receiving the communication signal, a signal output and a bias input;

the method comprising;

receiving said communication signal and removing modulation components from said communication signal to provide a detector output signal;

providing a TPC signal;

processing said TPC signal and said detector output signal to generate a current signal;

receiving said current signal and feedback from the output of said RF power amplifier and comparing said current signal with said feedback to produce a bias signal; and

dynamically adjusting the bias point of said amplifier using said bias signal.

7. The method of

claim 6

, whereby said processing step includes weighting both said TPC signal and said detector output signal and then combining said TPC and detector output signals.

8. The method of

claim 6

, whereby said comparing step further includes scaling said current signal and said feedback signal prior to said comparison.

9. The method of

claim 7

, whereby said comparing step further includes scaling said current signal and said feedback signal prior to said comparison.

10. The method of

claim 6

, whereby said communication signal is a CDMA signal.