Tuning circuitry in a communications device

• US 8,280,319 B2
• Filed: 06/28/2010
• Issued: 10/02/2012
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Kasha, Dan B., Rafi, Aslamali A., Kammula, Abhishek V., Vancorenland, Peter J., Tuttle, George T.
• Primary Examiner(s): Nguyen, Simon
• Application Number:
  US12/824,908
• Publication Number:
  US 20100267350A1
• Time in Patent Office: 827 Days
• Field of Search: 455120-125, 455/129, 455/575.7, 455/91, 455120-1271
• US Class Current: 455/91
• CPC Class Codes: H04B 1/0458 Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages matching circuits in general H03H

Abstract

A communications device is provided. The communications device includes a first antenna port coupled to a signal line, transmitter circuitry coupled to the signal line and configured to broadcast a radio frequency (RF) output signal across the first antenna port, tuning circuitry coupled to the signal line, and a controller configured to adjust a tuning of the tuning circuitry. The first antenna port, the transmitter circuitry, the tuning circuitry, and the controller are at least partially integrated on the same integrated circuit.

Claims

1. A communications device comprising:

a first antenna port coupled to a signal line;

transmitter circuitry including first output stage circuitry coupled to the signal line and configured to generate a radio frequency (RF) output signal having an RF frequency across the first antenna port, the first output stage circuitry forming a first amplifier that provides a first impedance on the first antenna port;

tuning circuitry coupled to the signal line, the tuning circuitry comprising at least one variable capacitor coupled in parallel with at least one inductor between the signal line and a first node;

level detect circuitry configured to detect the amplitude of the RF output signal on the signal line and to provide information corresponding to the detected amplitude of the RF output signal; and

a controller configured to receive the information corresponding to the detected amplitude of the RF output signal from the level detect circuitry, and to adjust a capacitance of the tuning circuitry to increase the amplitude of the RF output signal on the signal line.

2. The communications device of claim 1 wherein the first node comprises ground;

where the tuning circuitry includes at least one variable capacitor connected in parallel with at least one inductor between the signal line and ground, and wherein the inductor provides an impedance that, at least in part, generates the amplitude of the RF output signal on the signal line.

3. The communications device of claim 1 further comprising:

an antenna coupled to the first antenna port with the at least one variable capacitor and the at least one inductor of the tuning circuitry each being coupled to the signal line at a second node between the antennae and the transmitter circuitry.

4. The communications device of claim 3 wherein the amplifier comprises a high impedance amplifier;

and where the antenna comprises a high impedance antenna having an impedance of at least one kilo-ohm.

5. The communications device of claim 3 wherein the controller is configured to adjust the capacitance of the tuning circuitry to resonate the antenna.

6. The communications device of claim 1 wherein the controller is configured to adjust the capacitance of the tuning circuitry to resonate an antenna coupled to the first antenna port.

7. The communications device of claim 1 further comprising:

a second antenna port; and

second output stage circuitry having an input coupled to the signal line and configured to broadcast a second RF output signal generated from the first RF output signal across the second antenna port, the second output stage circuitry forming a second amplifier that provides a second impedance on the second antenna port;

where the first amplifier comprises a high impedance amplifier and the first impedance is a high impedance, and where the second amplifier comprises a low impedance amplifier and the second impedance comprises a low impedance.

8. The communications device of claim 1, where the first node comprises ground;

and wherein the tuning circuitry includes a a plurality of cells, each of the plurality of cells including a capacitive element coupled in series with a switch between the signal line and ground.

9. The communications device of claim 1 wherein the controller is configured to adjust a resistance of the tuning circuitry.

10. The communications device of claim 1, where the controller is further configured to iteratively adjust the capacitance of the tuning circuitry to maximize the amplitude of the RF output signal on the signal line.

11. A method performed by a controller in a communications device, the method comprising:

generating a radio frequency (RF) output signal having an RF frequency from transmitter circuitry;

adjusting a capacitance of tuning circuitry coupled on a signal line between the transmitter circuitry and a first antenna port to increase an amplitude of the radio frequency (RF) output signal on the signal line, the tuning circuitry comprising at least one variable capacitor coupled in parallel with at least one inductor between the signal line and a first node; and

detecting the amplitude of the RF output signal on the signal line subsequent to adjusting the capacitance.

12. The method of claim 11 wherein the first node comprises ground;

where the tuning circuitry includes at least one variable capacitor coupled in parallel with at least one inductor between the signal line and ground, and wherein the inductor provides an impedance that, at least in part, generates the amplitude of the RF output signal on the signal line.

13. The method of claim 11 further comprising:

adjusting the capacitance of the tuning circuitry to resonate an antenna coupled to the first antenna port.

14. The method of claim 13 wherein the first amplifier comprises a high impedance amplifier;

and where the antenna comprises a high impedance antenna having an impedance of at least one kilo-ohm.

15. The method of claim 11, where the first node comprises ground;

and where the method further comprises;

adjusting the capacitance of the tuning circuitry by adjusting a plurality of cells, each of the plurality of cells including a capacitive element coupled in series with a switch between the signal line and ground.

16. The method of claim 11 further comprising:

adjusting a resistance of the tuning circuitry.

17. The method of claim 11, further comprising iteratively performing the steps of adjusting the capacitance of the tuning circuitry and then detecting the amplitude of the RF output signal to maximize the amplitude of the RF output signal on the signal line.

18. A communications system comprising:

an antenna;

a communications device including;

an antenna port coupled to a signal line and the antenna;

transmitter circuitry including output stage circuitry coupled to the signal line and configured to generate a radio frequency (RF) output signal across the antenna, the output stage circuitry forming an amplifier that provides a first impedance on the antenna port;

tuning circuitry coupled to the signal line, the tuning circuitry comprising at least one variable capacitor coupled in parallel with at least one inductor between the signal line and a first node;

level detect circuitry configured to detect the amplitude of the RF output signal on the signal line and to provide information corresponding to the detected amplitude of the RF output signal; and

a controller configured to receive the information corresponding to the detected amplitude level of the RF output signal from the level detect circuitry, and to adjust a capacitance of the tuning circuitry to increase an amplitude of the RF output signal provided to the antenna; and

an input/output system configured to communicate with the communications device.

19. The communications system of claim 18 wherein the first node comprises ground;

where the tuning circuitry includes at least one variable capacitor coupled in parallel with at least one inductor between the signal line and ground, and wherein the inductor provides an impedance that, at least in part, generates the amplitude of the RF output signal on the high impedance antenna.

20. The communications system of claim 18 wherein the first amplifier comprises a high impedance amplifier;

and where the antenna comprises a high impedance antenna having an impedance of at least one kilo-ohm.

21. The communications system of claim 18 wherein the controller is configured to adjust the capacitance of the tuning circuitry to resonate the high impedance antenna.

22. The communications system of claim 18, where the first node comprises ground;

and wherein the tuning circuitry includes a a plurality of cells, each of the plurality of cells including a capacitive element coupled in series with a switch between the signal line and ground.

23. The communications system of claim 18, where the controller is further configured to iteratively adjust the capacitance of the tuning circuitry to maximize the amplitude of the RF output signal on the signal line.