Impedance tuning circuit

Patent metadata

Field	Value
Publication number	US-2016268992-A1
Application number	US-201514645177-A
Country	US
Kind code	A1
Filing date	Mar 11, 2015
Priority date	Mar 11, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A circuit for tuning an impedance matching network is disclosed. The circuit includes a current sensor, a control circuit coupled to the current sensor and a reference current source and a tunable capacitor coupled to the control circuit. The control circuit is configured to generate a control signal based on an output of the current sensor, wherein the control signal is configured to vary a capacitance of the tunable capacitor.

First claim

What is claimed is:

1 . A circuit, comprising:
a current sensor; a control circuit coupled to the current sensor and a reference current source; and a tunable capacitor coupled to the control circuit, wherein the control circuit is configured to generate a control signal based on an output of the current sensor, wherein the control signal is configured to vary a capacitance of the tunable capacitor.

2 . The circuit of claim 1 , wherein the tunable capacitor is coupled to an antenna tuning pin.

3 . The circuit of claim 1 , wherein the tunable capacitor includes a plurality of switchable capacitor circuits.

4 . The circuit of claim 2 , wherein each of the plurality of switchable capacitor circuits including a capacitor coupled to ground via a switch.

5 . The circuit of claim 4 , wherein the switch is controllable by the control signal.

6 . The circuit of claim 1 , wherein the tunable capacitor is coupled to an electrostatic discharge protection circuit.

7 . The circuit of claim 3 , wherein the control signal includes a plurality of bits, each of the plurality of bits coupled to a different switchable circuit in the plurality of switchable capacitor circuits.

8 . The circuit of claim 6 , wherein the control signal is an analog signal and the tunable capacitor is a voltage controlled variable capacitor.

9 . The circuit of claim 1 , wherein the tunable capacitor has a minimum and a maximum capacitance and the tunable capacitor includes:
a plurality of capacitors, each of the plurality of capacitors having a capacitance substantially less than the maximum capacitance, wherein each of the plurality of capacitors is coupled to a ground through a separate switching element; and an input port to receive a binary signal, a bit of the binary signal being coupled to the switch of the each of the plurality of capacitors.

10 . The circuit of claim 9 , wherein the tunable capacitor further including an electro static protection circuit.

11 . The circuit of claim 9 , wherein the tunable capacitor further including a port to receive a bias voltage.

12 . A system, comprising:
an antenna; an impedance matching circuit; and an integrated circuit including a circuit for automatically tuning a variable capacitor based on an impedance mismatch between the impedance matching circuit and the antenna.

13 . The system of claim 12 , wherein the antenna is fabricated on a printed circuit board.

14 . The system of claim 13 , wherein the integrated circuit is mounted on the same printed circuit board.

15 . The system of claim 12 , wherein the integrated circuit is configured to detect a current corresponding to the impedance mismatch between the impedance matching circuit and the antenna and generate a binary signal corresponding to the detected current.

16 . The system of claim 15 , wherein the binary signal is used to vary capacitance of the variable capacitor.

17 . The system of claim 12 , wherein the variable capacitor includes a plurality of capacitors, each of the plurality of capacitors coupled to a ground through a switch.

18 . A circuit, comprising:
a voltage regulator; a current sensor coupled to the voltage regulator; a voltage sensor; a power amplifier coupled to the voltage sensor and current sensor; and a controller coupled to the current sensor and the voltage sensor, wherein the controller is configured to produce a control signal based on inputs from the current sensor and the voltage sensor.

19 . The circuit of claim 18 , wherein the controller is coupled to current and voltage references and includes a comparator circuit that compares input from the current sensor and input from the voltage sensor to the current and voltage references respectively, to produce the control signal.

20 . The circuit of claim 18 , wherein the controller is programmable and executed by a processor.

Assignees

• Nxp Bv

Inventors

• Salfelner Anton
• Velandia Torres Javier Mauricio

Classifications

• H03H2210/025

  Capacitor · CPC title

• H01Q7/00

  Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop · CPC title

• H03H7/40 Primary

  Automatic matching of load impedance to source impedance · CPC title

• H03K5/24

  the characteristic being amplitude · CPC title

• H01Q1/50

  Structural association of antennas with earthing switches, lead-in devices or lightning protectors · CPC title