Method and apparatus for reducing charge and discharge time of capacitive elements

• US 9,337,875 B2
• Filed: 09/10/2013
• Issued: 05/10/2016
• Est. Priority Date: 06/05/2013
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Blackberry Limited
• Inventors: Greene, Matthew Russell, Oakes, James, Blin, Guillaume
• Primary Examiner(s): HUANG, WEN WU
• Application Number:
  US14/022,765
• Publication Number:
  US 20140364069A1
• Time in Patent Office: 973 Days
• Field of Search: 455/107, 455/248.1, 455/320
• US Class Current: 1/1
• 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 system that incorporates teachings of the subject disclosure may include, for example, emulating a behavior of an RF capacitive device utilizing a mirror circuit; and providing feedback signals to an input of an operational amplifier via a feedback node coupled with the mirror circuit. Other embodiments are disclosed.

Claims

1. A communication device, comprising:

an antenna;

a transceiver coupled with the antenna;

an RF capacitive device coupled with the antenna and the transceiver, wherein the RF capacitive device comprises;

a device capacitor;

a first resistive device coupled between a biasing node and one end of the device capacitor; and

a second resistive device coupled between another end of the device capacitor and electrical ground; and

an operational amplifier coupled with the RF capacitive device by way of the biasing node, wherein the RF capacitive device operates according to a first time constant; and

a mirror circuit comprising a capacitive portion, wherein the capacitive portion comprises;

a mirror capacitor;

a first mirror resistive device coupled between the biasing node and one end of the mirror capacitor; and

a second mirror resistive device coupled between another end of the mirror capacitor and electrical ground, wherein the capacitive portion operates according to a second time constant, wherein the mirror circuit emulates a time and frequency response of the RF capacitive device, wherein the second time constant is based on the first time constant, and wherein feedback signals from the mirror circuit are provided to an input of the operational amplifier via a feedback node coupled with the mirror circuit.

2. The communication device of claim 1, wherein the feedback signals are based on measurements directly across the mirror capacitor.

3. The communication device of claim 1, wherein the capacitive portion of the mirror circuit includes a fixed capacitor without a voltage tunable dielectric capacitor.

4. The communication device of claim 1, wherein the capacitive portion of the mirror circuit includes a voltage tunable dielectric capacitor.

5. The communication device of claim 1, wherein the RF capacitive device includes a voltage tunable dielectric capacitor.

6. The communication device of claim 1, wherein the mirror capacitor is adjustable based on a predetermined final voltage.

7. The communication device of claim 1, wherein the mirror circuit is adjustable based on a capacitance vs. bias voltage response of the mirror capacitor.

8. The communication device of claim 1, wherein the mirror circuit is adjustable based on one of the first time constant or the second time constant.

9. The communication device of claim 1, wherein a first product of the first mirror resistive device and the mirror capacitor is greater than a second product of the first resistive device and the device capacitor.

10. The communication device of claim 1, comprising a step-up DC/DC voltage converter coupled with the operational amplifier that generates an increased positive voltage supply from a default power supply and provides the increased positive voltage supply to the operational amplifier.

11. The communication device of claim 1, comprising an inverter DC/DC voltage converter coupled with the operational amplifier that generates a decreased negative voltage supply from a default power supply and provides the decreased negative voltage supply to the operational amplifier.

12. The communication device of claim 1, wherein the RF capacitive device is utilized in an open loop control system for performing impedance matching.

13. The communication device of claim 12, wherein the open loop control system performs impedance tuning based in part on a use case of the communication device.

14. The communication device of claim 1, further comprising a matching network, wherein the RF capacitive device is part of the matching network and is utilized in a closed loop control system for performing impedance matching.

15. An apparatus, comprising:

a matching network comprising a first capacitive circuit in electrical communication with a biasing node, wherein the matching network provides impedance matching during RF communications, wherein the first capacitive circuit operates according to a first time constant;

an operational amplifier in electrical communication with the biasing node;

a mirror circuit comprising second capacitive circuit in electrical communication with the biasing node, wherein the mirror circuit emulates an RF behavior associated with at least a portion of the matching network, including emulating a time and frequency response of the at least a portion of the matching network;

a memory that stores executable instructions; and

a controller; and

a memory that stores executable instructions that, when executed by the controller, facilitate performance of operations, comprising;

determining a driving voltage to be applied to the second capacitive circuit to achieve a predetermined operational result associated with the RF communications, wherein the second capacitive circuit operates according to a second time constant that is based on the first time constant; and

applying a first bias voltage to the second capacitive circuit, wherein the first bias voltage is higher than the driving voltage for a first duration to reduce a charge time, wherein the first duration is determined based on a capacitance vs. bias voltage response of the second capacitive circuit, the second time constant and a capacitance value of the second capacitive circuit.

16. The apparatus of claim 15, wherein the mirror circuit operates according to a second time constant based on the first time constant, wherein feedback signals from the mirror circuit are provided to an input of the operational amplifier via a feedback node coupled with the mirror circuit.

17. The apparatus of claim 16, wherein the matching network performs an open loop impedance matching process utilizing the first capacitive circuit.

18. The apparatus of claim 16, wherein the matching network performs a closed loop impedance matching process utilizing the first capacitive circuit.

19. A communication device, comprising:

an antenna;

a transceiver coupled with the antenna;

an impedance matching circuit coupled between the antenna and the transceiver, wherein the impedance matching circuit comprises a first RC circuit operating according to a first time constant;

an operational amplifier coupled with the impedance matching circuit; and

a second RC circuit coupled with the operational amplifier and the impedance matching circuit, wherein the second RC circuit includes a serial connection of resistive elements with a capacitive element positioned between the resistive elements to cause the second RC circuit to operate according to a second time constant that is based on the first time constant, wherein the second RC circuit emulates a time and frequency response of the first RC circuit, and wherein feedback signals for the operational amplifier are measured directly across the capacitive element to facilitate tuning of the impedance matching circuit.

20. The communication device of claim 19, wherein the capacitive element includes a voltage tunable dielectric capacitor.