Impedance conversion circuit, antenna apparatus, and wireless communication apparatus

Patent metadata

Field	Value
Publication number	US-2016182003-A1
Application number	US-201615057147-A
Country	US
Kind code	A1
Filing date	Mar 1, 2016
Priority date	Sep 5, 2013
Publication date	Jun 23, 2016
Grant date	—

Abstract

An impedance conversion circuit includes an auto-transformer circuit including a first inductor connected between a first port connected on a power supply portion side and a second port connected on an antenna side and a second inductor connected between a third port that is grounded and the second port; a first phase shifter with a first end connected to the first port; an inductor connected in series between a second end of the first phase shifter and the power supply portion; and a capacitor connected in series to the inductor and connected in series between the second end of the first phase shifter and the power supply portion.

First claim

What is claimed is:

1 . An impedance conversion circuit comprising:
an auto-transformer circuit including a first inductor connected between a first port connected on a power supply side and a second port connected on an antenna side and a second inductor connected between a third port that is grounded and the second port, the first inductor and the second inductor being coupled to each other; a first phase shifter including a first end connected to the first port of the auto-transformer circuit; an inductor connected in series between a second end of the first phase shifter and the power supply; and a capacitor connected in series to the inductor and connected in series between the second end of the first phase shifter and the power supply.

2 . The impedance conversion circuit according to claim 1 , wherein
when a region in polar coordinates where a real part is positive and an imaginary part is positive of a reflection coefficient defines and serves as a first quadrant, a region in the polar coordinates where the real part is negative and the imaginary part is positive of the reflection coefficient defines and serves as a second quadrant, a region in the polar coordinates where the real part is negative and the imaginary part is negative of the reflection coefficient defines and serves as a third quadrant, and a region in the polar coordinates where the real part is positive and the imaginary part is negative of the reflection coefficient defines and serves as a fourth quadrant, among trajectories of the reflection coefficient when viewing the second port side from the first port obtained by making a frequency sweep, the auto-transformer circuit shifts a center of a first trajectory that is a trajectory in a low band to the first quadrant or the second quadrant and shifts a center of a second trajectory that is a trajectory in a high band to the first quadrant or the fourth quadrant; the first phase shifter rotates the first trajectory so that a center thereof is in the first quadrant and rotates the second trajectory so that a center thereof is in the fourth quadrant; the capacitor moves the center of the first trajectory toward a center of the polar coordinates; and the inductor moves the center of the second trajectory toward the center of the polar coordinates.

3 . The impedance conversion circuit according to claim 2 , wherein the center of the first trajectory is a position in the polar coordinates that takes an average of a maximum value and a minimum value of the real part of the reflection coefficient as the real part and an average of the maximum value and the minimum value of the imaginary part as the imaginary part for the first trajectory, and the center of the second trajectory is a position in the polar coordinates that takes an average of a maximum value and a minimum value of the real part of the reflection coefficient as the real part and an average of the maximum value and the minimum value of the imaginary part as the imaginary part for the second trajectory.

4 . The impedance conversion circuit according to claim 2 , wherein the center of the first trajectory is an intermediate point in the polar coordinates between the reflection coefficient at a lower limit frequency and the reflection coefficient at an upper limit frequency in the low band, and the center of the second trajectory is an intermediate point in the polar coordinates between the reflection coefficient at a lower limit frequency and the reflection coefficient at an upper limit frequency in the high band.

5 . The impedance conversion circuit according to claim 2 , wherein the center of the first trajectory is a position corresponding to an average of the reflection coefficients at each of frequencies located at equal frequency intervals in the trajectory of the low band, and the center of the second trajectory is a position corresponding to an average of the reflection coefficients at each of frequencies located at equal frequency intervals in the trajectory of the high band.

6 . The impedance conversion circuit according to claim 2 , wherein the shifting of the first trajectory and the shifting of the second trajectory by the auto-transformer circuit are produced by an inductance arising in parallel and an inductance arising in series in an equivalent circuit of the auto-transformer circuit.

7 . The impedance conversion circuit according to claim 1 , further comprising a second phase shifter connected between the inductor and the capacitor.

8 . The impedance conversion circuit according to claim 7 , wherein the inductor is connected on the power supply side, and the capacitor is connected on the first phase shifter side.

9 . The impedance conversion circuit according to claim 7 , wherein the inductor is connected on the first phase shifter side, and the capacitor is connected on the power supply side.

10 . The impedance conversion circuit according to claim 7 , wherein the second phase shifter includes a transmission line or a delay line.

11 . The impedance conversion circuit according to claim 1 , wherein the first phase shifter includes a transmission line or a delay line.

12 . The impedance conversion circuit according to claim 1 , wherein the first phase shifter is located in a multilayer body of the impedance conversion circuit or on a mounting board on which the impedance conversion circuit is mounted.

13 . The impedance conversion circuit according to claim 7 , wherein the second phase shifter is located in a multilayer body of the impedance conversion circuit or on a mounting board on which the impedance conversion circuit is mounted.

14 . An antenna apparatus comprising:
the impedance conversion circuit according to claim 1 ; and an antenna connected to the second port of the auto-transformer circuit of the impedance conversion circuit.

15 . The antenna apparatus according to claim 14 , wherein the antenna is one of a T-branched antenna element, a monopole antenna, and an inverted-F antenna.

16 . A wireless communication apparatus comprising:
the impedance conversion circuit according to claim 1 ; an antenna connected to the second port of the auto-transformer circuit of the impedance conversion circuit; and a communication circuit that includes the power supply.

17 . The wireless communication apparatus according to claim 16 , wherein the wireless communication apparatus is a cellular phone.

18 . The wireless communication apparatus according to claim 16 , wherein the antenna is one of a T-branched antenna element, a monopole antenna, and an inverted-F antenna.

Assignees

• Murata Manufacturing Co

Inventors

• Teshima yuichiro
• Ishizuka Kenichi

Classifications

• H04B1/0458

  Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages (matching circuits in general H03H) · CPC title

• H03H7/38 Primary

  Impedance-matching networks · CPC title

• H01P1/20345

  Multilayer filters · CPC title

• H04B1/18

  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) · CPC title

• H01Q1/243

  with built-in antennas · CPC title