Variable matching circuit

• US 7,633,355 B2
• Filed: 04/19/2005
• Issued: 12/15/2009
• Est. Priority Date: 04/22/2004
• Status: Expired due to Fees

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Matsuo, Michiaki
• Primary Examiner(s): Jones; Stephen E
• Application Number:
  US11/568,188
• Publication Number:
  US 20080238569A1
• Time in Patent Office: 1,701 Days
• Field of Search: 333/32, 333/17.3, 333/81.R, 333/124, 333/129, 333/132, 333/167, 333/174, 333/175, 333/176
• US Class Current: 333/32
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H

Abstract

A variable matching circuit includes a variable capacitance circuit formed of a capacitor coupled to varactor diode and provided between terminals, and a resonator-type circuit includes a plurality of inductors and a variable capacitance circuit formed of a capacitor and a varactor diode. The inductors and the variable capacitance circuit are coupled in parallel together. The resonator-type circuit is connected in shunt with the terminal. The foregoing structure forms an L-type matching circuit. The bias of the varactor diodes can be thus varied, and plural values of the inductance of the resonator-type circuit can be switched over with a FET. The variable matching circuit can electrically control an impedance conversion available for wider ranges of frequency bandwidths.

Claims

1. A variable matching circuit comprising:

a resonator-type circuit including;

an inductance circuit having a first end grounded and a variable inductance value;

a first capacitance circuit coupled in parallel to the inductance circuit and having a variable capacitance; and

a second capacitance circuit coupled to a second end of the inductance circuit and having a variable capacitance

wherein the inductance circuit includes a plurality of inductors coupled in series together and a switch coupled in parallel to at least one of the plurality of inductors.

2. The variable matching circuit of claim 1, wherein a distributed constant line is provided between the resonator-type circuit and the second capacitance circuit.

3. The variable matching circuit of claim 1, wherein a distributed constant line is provided between the resonator-type circuit and the second capacitance circuit.