Phase inverter and push-pull amplifier using the same

Claim 2

A phase inverter as claimed in claim 1, characterized in that said first coupling circuit (100₁) has two ends which are both open, and said fourth coupling circuit has two ends which are grounded so that said first coupling circuit is different in type from said fourth coupled circuit.

Claim 3

A phase inverter as claimed in claim 1, characterized in that said first coupling circuit (100₁) has two ends which are both grounded, and said fourth coupling circuit (100₄) has two ends which are both open so that said first coupling circuit is different in type from said fourth coupling circuit.

Claim 4

A phase inverter as claimed in any of claims 1 to 3, characterized in that each of said second and third coupling circuits (100₂, 100₃) has two ends which are both open so that said second and third coupling circuits are of the same type.

Claim 5

A phase inverter as claimed in any of claims 1 to 3, characterized in that each of said second and third coupling circuits (100₂, 100₃) has two ends which are both grounded so that said second and third coupling circuits are of the same type.

Claim 6

A phase inverter as claimed in any of claims 1 to 5, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises two coupled lines (10₁ - 10₄) each having a length of λ/4 where λ is a wavelength of each of said input and output signals.

Claim 7

A phase inverter as claimed in any of claims 1 to 5, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises three or more λ/4 interdigital coupled lines (35₁ - 35₄) where λ is a wavelength of each of said input and output signals.

Claim 8

A phase inverter as claimed in any of claims 1 to 5, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises a directional coupler (35₁ - 35₄).

Claim 9

A phase inverter as claimed in claim 6, characterized in that said two coupled lines (10₁ - 10₄) have an identical width.

Claim 10

A phase inverter as claimed in claim 6, characterized in that one (W1) of said two coupled lines is wider than the other coupled line (W2).

Claim 11

A phase inverter as claimed in any of claims 1 to 5, characterized in that: each of said first to fourth coupling circuits (100₁ - 100₄) has a first line (W2) and a second line (W1) wider than said first line, said first and second lines each have a length of λ/4 where λ is a wavelength of each of said input and output signals and are arranged in parallel to thereby form coupled lines, said first line of each of said first and fourth coupling circuit is coupled to said first terminal (50), said first line of each of said second and third coupling circuit is connected to said third terminal (52), said second line of each of said first and second coupling circuits is coupled to said second terminal (51), said second line of each of said third and fourth coupling circuits is coupled to said fourth terminal (53), and an impedance of each of said second and fourth terminals is lower than that of each of said first and third terminals.

Claim 12

A phase inverter as claimed in any of claims 1 to 5, characterized in that:

Claim 13

each of said first to fourth coupling circuits (100₁ - 100₄) has a first group of lines mutually connected, a second group of lines (W1, W3) mutually connected, the lines of said first and second groups have an interdigital arrangement, the lines of said second group are wider than the lines of said first group, said first group of lines of each of said first and fourth coupling circuit is coupled to said first terminal (60), said first group of lines of each of said second and third coupling circuit is connected to said third terminal (62), said second group of lines of each of said first and second coupling circuits is coupled to said second terminal (61), said second group of lines of each of said third and fourth coupling circuits is coupled to said fourth terminal (63), and an impedance of each of said second and fourth terminals is lower than that of each of said first and third terminals.

Claim 14

A phase inverter as claimed in any of claims 1 to 5, characterized in that said first to fourth coupling circuits (100₁ - 100₄) respectively comprises first to fourth waveguide directional couplers (70₁ - 70₄) each having a short-circuit element (73₁ - 73₄) and having input (A), main (B), couple (C) and isolation (D) ports, and first to fourth branch waveguides (71₁ - 71₄) each having first, second and third branches, and in that: said first branch waveguide (71₁) couples said first and fourth waveguide directional couplers (70₁, 70₄) through said input and isolation ports thereof and said first and second branches of said first branch waveguide, the third branch thereof serving as said first terminal (72₁), said second branch waveguide (71₂) couples said first and second waveguide directional couplers (70₁, 70₂) through said input and isolation ports and said first and second branches of said second branch waveguide, the third branch thereof serving as said second terminal (72₂), said third branch waveguide (71₃) couples said second and third waveguide directional couplers (70₂, 70₃) through said input and isolation ports thereof and said first and second branches of said third branch waveguide, the third branch thereof serving as said third terminal (72₃), said fourth branch waveguide (71₄) couples said third and fourth waveguide directional couplers (70₃, 70₄) through said input and isolation ports and said first and second branches of said fourth branch waveguide, the third branch thereof serving as said fourth terminal (71₄), and said short-circuit element (73₁ - 73₄) is provided for said main and couple ports of each of said first to fourth waveguide directional couplers.

Claim 15

A phase inverter as claimed in claim 13, characterized in that said short-circuit element for said fourth waveguide directional coupler (80₄) has an elongated waveguide (82) directly coupled to said main and couple ports of said fourth waveguide directional coupler, and a short-circuit plate (83₄) which short-circuits said elongated waveguide, and in that said short-circuit element for each of said first to third waveguide directional couplers (80₁ - 80₃) includes a short-circuit element (84₁- 84₃) which short-circuits said main and couple ports of each of said first to third waveguide directional couplers.

Claim 16

A phase inverter as claimed in claim 13, characterized in that said short-circuit element (71₁ - 73₃) provided for each of said first to third waveguide directional couplers (70₁ - 70₃) includes an elongated waveguide (82) directly coupled to said main and couple ports thereof and a short-circuit plate (83₁ - 83₃) short-circuiting said elongated waveguide, and in that said short-circuit element provided for said fourth waveguide directional coupler (70₄) includes a short-circuit plate (83₄) which short-circuits said main and couple ports thereof.

Claim 17

A phase inverter as claimed in claim 14, characterized in that said elongated waveguide (82) has a length corresponding to the 180° phase difference between said first and fourth terminals.

Claim 18

A phase inverter as claimed in claim 15, characterized in that each of said elongated waveguides (82) has a length corresponding to the 180° phase difference between said first and fourth terminals.

Claim 19

A phase inverter as claimed in any of claims 13 to 17, characterized in that each of said first to fourth waveguide directional couplers is selected from the group consisting of a magnetic field coupling type waveguide directional coupler (FIG.14A) and an electric field coupling type waveguide directional coupler (FIG.14B).

Claim 20

A push-pull amplifier comprising: a first phase inverter (90) having an input terminal receiving an input signal and two output terminals; a second phase inverter (91) having two input terminals and an output terminal outputting an output signal; a first amplifier (A1) coupled between one of said two output terminals of said first phase inverter and one of said two input terminals of said second phase inverter; and a second amplifier (A2) coupled between the other output terminal of said first phase inverter and the other input terminal of said second phase inverter, each of said first and second phase inverters including: first, second, third and fourth terminals (101- 104); a first coupling circuit (100₁) coupled between said first and second terminals; a second coupling circuit (100₂) coupled between said second and third terminals; a third coupling circuit (100₃) coupled between said third and fourth terminals; and a fourth coupling circuit (100₄) coupled between said first and fourth terminals, said first to fourth terminals and said first to fourth coupling circuits being arranged into a ring, said first coupling circuit being of a type different from a type of said fourth coupling circuit, and said second and third coupling circuits being identical in type, said first, second, and fourth terminals of said first phase inverter being said input terminal and said two output terminals thereof, respectively, said first, second and fourth terminals of said second phase inverter being said two input terminals and said output terminal thereof, respectively, and said third terminals of said first and second phase inverters being grounded through first and second resistors (R1, R2), respectively.

Claim 21

A push-pull amplifier as claimed in claim 19, characterized in that said first coupling circuit (100₁) has two ends which are both open, and said fourth coupling circuit (100₄) has two ends which are grounded so that said first coupling circuit is different in type from said fourth coupling circuit.

Claim 22

A push-pull amplifier as claimed in claim 19, characterized in that said first coupling circuit (100₁) has two ends which are both grounded, and said fourth coupling circuit (100₄) has two ends which are both open so that said first coupling circuit is different in type from said fourth coupling circuit.

Claim 23

A push-pull amplifier as claimed in claim 19, characterized in that each of said second and third coupling circuits (100₂, 100₃) has two ends which are both open so that said second and third coupling circuits are of the same type.

Claim 24

A push-pull amplifier as claimed in claim 19, characterized in that each of said second and third coupling circuits (100₂, 100₃) has two ends which are both grounded so that said second and third coupling circuits are of the same type.

Claim 25

A push-pull amplifier as claimed in any of claims 19 to 23, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises two coupled lines (10₁ - 10₄) each having a length of λ/4 where λ is a wavelength of each of said input and output signals.

Claim 26

A push-pull amplifier as claimed in any of claims 19 to 23, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises three or more λ/4 interdigital coupled lines (35₁ - 35₄) where λ is a wavelength of each of said input and output signals.

Claim 27

A push-pull amplifier as claimed in any of claims 19 to 23, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises a directional coupler (35₁ - 35₄).

Claim 28

A push-pull amplifier as claimed in any of claims 19 to 23, characterized in that each of said first to fourth coupling circuits (100₁ - 100₄) comprises a waveguide directional amplifier (80₁ - 80₄).

Claim 29

A push-pull amplifier as claimed in any of claims 19 to 27, characterized in that each of said first and second amplifiers (A1, A2) has a B-class amplifying function.