Method and apparatus for wireless phone transmit power amplification with reduced power consumption

• US 6,313,698 B1
• Filed: 09/24/1999
• Issued: 11/06/2001
• Est. Priority Date: 09/24/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhang, Yang, Peng, Yongsheng
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US09/404,890
• Time in Patent Office: 774 Days
• Field of Search: 330/51, 330/133, 330/134, 330/150, 330/151
• US Class Current: 330/51
• 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 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 2203/7215 the gated amplifier being switched on or off by a switch at the input of the amplifier
• CPC Class Codes: H03F 2203/7221 the gated amplifier being switched on or off by a switch at the output of the amplifier
• CPC Class Codes: H03F 2203/7239 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers and shunting lines by one or more switch(es)
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 2001/0416 having gain or transmission power control
• CPC Class Codes: H04B 2001/045 with means for improving efficiency

Abstract

A method and apparatus for RF amplification of a transmit signal within a wireless phone. The amplifier chain is composed of three parts, a pre-driver, a bypassable driver amp, and a power amp. The configuration of the amplifier chain is adjusted in real time to optimize power consumption for a given output power requirement. At low output power levels the driver amp is bypassed and the power amp is provided a low bias current. At medium output power levels the driver amp is bypassed and the power amp is biased at a moderate current. When high output power is required the driver amp is utilized and the power amp is provided a high bias current. The driver amp is shut down when in the bypassed state. The result of implementing this amplifier configuration is an increase in the efficiency of the transmit amplifier. The increase in amplifier efficiency results in increased talk times for battery powered wireless phones.

Claims

1. An RF amplifier for a wireless phone comprising:

a pre-driver amplifier;

a driver amplifier;

a bandpass filter with an input connected to an output of the driver amplifier;

a high power amplifier;

a first RF switch having an input connected to an output of the pre-driver amplifier with a first switch output connected to an input of the driver amplifier;

a second RF switch having an output connected to an input of the high power amplifier, a first input connected to the output of the bandpass filter, and a second input connected to a second output of the first RF switch such that the driver amplifier and bandpass filter can be switchably bypassed; and

a power control logic circuit that inputs data control bits and provides corresponding output signals that control the first and second RF switch positions and controls a bias current of the high power amplifier to one of a plurality of active bias levels.

2. The RF amplifier of claim 1 wherein the power control logic also outputs a signal that controls the driver amplifier to an ON or OFF state.

3. The RF amplifier of claim 2 wherein the power control logic controls the driver amplifier to an ON state when the RF switches are positioned to connect the pre-driver amplifier to the driver amplifier and the bandpass filter to the high power amplifier.

4. The RF amplifier of claim 3 wherein the power control logic outputs information controlling the bias current to the high power amplifier to a predetermined high level when the RF switches are positioned to connect the pre-driver amplifier to the driver amplifier and the bandpass filter to the high power amplifier.

5. The RF amplifier of claim 2 wherein the power control logic controls the driver amplifier to an OFF state when the RF switches are positioned to bypass the driver amplifier and bandpass filter.

6. A method for RF amplification in a wireless phone comprising:

providing a three stage amplifier comprising a pre-driver amplifier, a driver amplifier, and a high power amplifier;

inputting to power control logic on the amplifier one of a plurality of possible power control states;

configuring a signal path through the three stage amplifier according to the input power control state;

configuring a bias current supplied to the high power amplifier to one of a plurality of active bias levels according to the input power control state.

7. The method of claim 6 further comprising the steps:

configuring the driver amplifier to an ON or OFF state according to the input power control state.

8. The method of claim 7 wherein the bias current supplied to the high power amplifier is a first bias current when the power control state is a first power state.

9. The method of claim 7 wherein the bias current supplied to the high power amplifier is a second bias current greater than a first bias current when the power control state is a second power state, wherein the second power control state is defined as a range of amplifier output power greater than the amplifier output power in a first power control state.

10. The method of claim 7 wherein the bias current supplied to the high power amplifier is a third bias current greater than either a first or second bias current when the power control state is a third power state, wherein the third power control state is defined as a range of amplifier output power greater than the amplifier output power in a first or a second power control state.

11. The method of claim 6 wherein the signal path is configured to flow from the pre-driver amplifier to the high power amplifier and bypasses the driver amplifier when the power control state is a first power state or a second power state, wherein the second power state is defined as a range of amplifier output power greater than the amplifier output power in the first power state.

12. The method of claim 11 wherein the driver amp is configured to an OFF state when the input power control state is the first power state or the second power state.

13. The method of claim 6 wherein the signal path is configured to flow from the pre-driver amplifier to the driver amplifier and then to the high power amplifier when the input power control state is a third power state, wherein the third power state is defined as a range of amplifier output power greater than the amplifier output power in a first power state or a second power state.