METHOD AND APPARATUS FOR REDUCING PEAK CURRENT VARIATION IN A RADIO

• US 20100022209A1
• Filed: 07/25/2008
• Published: 01/28/2010
• Est. Priority Date: 07/25/2008
• Status: Abandoned Application

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Yeoh, Chen Kok, Ng, Chin Wun
• Application Number:
  US12/179,895
• Publication Number:
  US 20100022209A1
• Time in Patent Office: Days
• US Class Current: 455/127.200
• CPC Class Codes: H03F 1/34 Negative-feedback-circuit arrangements with or without positive feedback H03F1/02 - H03F1/30, H03F1/38 - H03F1/50, H03F3/50 take precedence ; for rejection of common mode signals H03F3/45479
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 1/0466 Fault detection or indication H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0433 with linearisation using feedback

Abstract

The application discloses a method and apparatus for reducing peak current variation in a radio. The method includes monitoring (202) output power of a power amplifier (106) and determining (204) that the output power of the power amplifier is above a predefined threshold. The method then includes controlling (206) input power of the power amplifier (106) so that the output power is reduced below the predefined threshold. The method further includes isolating the power amplifier (106) from receiving signals reflected from an antenna (112) such that the output power is maintained below the predefined threshold. The method then includes effecting (208) amplification of a radio frequency signal at the maintained output power in the linear region of operation such that the radio frequency signal is amplified with reduced peak current variation.

Claims

1. A method for reducing peak current variation in a radio, the method comprising:

monitoring output power of a power amplifier;

determining that the output power of the power amplifier is above a predefined threshold, the predefined threshold indicating a movement of the power amplifier towards a non-linear region of operation;

controlling input power of the power amplifier and isolating the power amplifier from receiving signals reflected from an antenna such that the output power is maintained below the predefined threshold to maintain the power amplifier in a linear region of operation; and

effecting amplification of a radio frequency signal at the maintained output power in the linear region of operation such that the radio frequency signal is amplified with reduced peak current variation.

2. The method of claim 1, wherein determining that the output power of the power amplifier is above the predefined threshold comprises:

receiving the output power of the power amplifier via a reverse feedback loop of the power amplifier; and

comparing the received output power with the predefined threshold so as to determine whether the output power is above the predefined threshold.

3. The method of claim 2, wherein controlling the input power of the power amplifier comprises reducing the input power supplied to the power amplifier when the received output power is above the predefined threshold.

4. The method of claim 3, wherein the input power of the power amplifier is controlled by a circular eliminator (CE).

5. The method of claim 1, wherein isolating the power amplifier from the signals reflected from the antenna comprises absorbing the signals reflected from the antenna so that the power amplifier is prevented from receiving the signals, wherein the signals are absorbed by passing the signals in a path unconnected to the power amplifier.

6. The method of claim 5, wherein the signals reflected from the antenna are due to change in impedance associated with the antenna.

7. The method of claim 1, wherein the power amplifier is isolated, from receiving signals reflected from an antenna, by an isolator coupled to an output of the power amplifier.

8. The method of claim 1, wherein effecting amplification of a radio frequency (RF) signal comprises amplifying the radio frequency signal without receiving additional current from a battery.

9. The method of claim 1, wherein the radio is a portable battery operated radio.

10. The method of claim 1, wherein the radio is a battery powered portable two-way radio.

11. The method of claim 1, wherein the radio operates in a terrestrial radio access network (TETRA) system.

12. An apparatus for reducing peak current variation in a radio, the apparatus comprising:

a circular eliminator for monitoring output power of a power amplifier, and controlling input power of the power amplifier when the monitored output power is above a predefined threshold, wherein the input power is controlled to reduce the output power below the predefined threshold;

an isolator for isolating the power amplifier from signals reflected from an antenna such that the output power is maintained below the predefined threshold, wherein the isolator is coupled to an amplitude training system for determining the peak current variation in the power amplifier; and

the power amplifier coupled to the circular eliminator and the isolator for amplifying a radio frequency signal at the maintained output power so as to reduce the peak current variation in the radio frequency signal.

13. The apparatus of claim 12, wherein the isolator is coupled to the antenna for absorbing signals reflected from the antenna so that the power amplifier is prevented from receiving the signals reflected from the antenna.

14. The apparatus of claim 12, wherein the power amplifier is coupled to a Cartesian feedback system for providing the output power of the power amplifier to the circular eliminator.

15. The apparatus of claim 12, wherein the isolator is decoupled from the amplitude training system so as to reduce the output power of the power amplifier, wherein the isolator is decoupled from the amplitude training system by removing the amplitude training system out of the radio.

16. The apparatus of claim 12, wherein the radio comprises at least one of a portable two-way hand-held radio or a mobile radio.

17. The apparatus of claim 12, wherein the radio is an atmosphere explosibles (ATEX) compliant radio.