Matching circuit for a microwave device

Claim 2

A matching circuit, for a microwave device, which is formed on a dielectric substrate and comprising: a main line formed between a high-frequency signal input terminal and an input terminal of a semiconductor element for transmitting a high frequency signal; a stub, formed close to said main line, for obtaining matching of said high-frequency input terminal with said semiconductor element; and a variable-impedance circuit, including at least a capacitor having one end connected to a portion of said main line and the other end connected to said stub, said capacitor exhibiting a high resistance with respect to unnecessary components at both said main line and the output of said semiconductor element, thus attenuating the unnecessary components.

Claim 3

A matching circuit according to claim 1, wherein said variable-impedance circuit comprises a resistor connected in parallel with said capacitor.

Claim 4

A matching circuit, for a microwave device, which is arranged on a dielectric substrate and comprising: a high-frequency signal-guiding main line for guiding a high-frequency signal to one end of a mixer diode; a local oscillation signal-guiding main line for guiding a local oscillation signal to the other end of said mixer diode; a low-pass filter line, connected to said other end of said mixer diode, and constituting a low-pass filter for outputting an intermediate-frequency signal; a stub, formed close to said high-frequency signal-guiding main line, for decreasing leakage of the local oscillation signal to the high freuqency input; and a capacitor, having one end, connected to a portion of said high-frequency signal-guiding main line and the other end connected to said stub, for absorbing a reflected component of the intermediate frequency signal.

Claim 5

A matching circuit, for a microwave device, which is arranged on a dielectric substrate and comprising: a high-frequency signal-guiding main line for guiding a high-frequency signal to one end of a mixer diode; a local oscillation signal-guiding main line for guiding a local oscillation signal to the other end of said mixer diode; a low-pass filter line, connected to said other end of said mixer diode, and constituting a low-pass filter for outputting an intermediate-frequency signal; a stub, formed close to said high-frequency signal-guiding main line, for decreasing leakage of the local oscillation signal to the high freuqency input; and a capacitor, having one end, connected to a portion of said high-frequency signal-guiding main line and the other end connected to said stub, for absorbing a reflected component of the intermediate frequency signal.

Claim 6

A matching circuit according to claim 3, wherein a capacitor for absorbing a reflected component of the intermediate-frequency signal is connected also between said local oscillation signal-guiding main line and said mixer diode.

Claim 7

A matching circuit, for a microwave device, which is formed on a dielectric substrate and comprising: a first main line connected between a signal input terminal and an input terminal of a semiconductor amplifying element; a first stub formed close to said first main line; a first variable-impedance circuit including at least a capacitor having one end connected to a portion of said first main line and the other end connected to said first stub, and having a low impedance with respect to a signal of a frequency band used and a high impedance, which provides a loss, with respect to a signal of a higher frequency band than the frequency band used; a second main line connected between an output terminal of said semiconductor amplifying element and a signal output terminal; a second stub formed close to said second main line; and a second variable-impedance circuit including at least one capacitor having one end connected to a portion of said second main line and the other end connected to said second stub, and having a low impedance with respect to the signal of the frequency band used and a high impedance, which provides a loss, with respect to a signal of a higher frequency band than the frequency band used.

Claim 8

A matching circuit, for a microwave device, which is formed on a dielectric substrate and comprising: a first main line connected between a signal input terminal and an input terminal of a semiconductor amplifying element; a first stub formed close to said first main line; a first variable-impedance circuit including at least a capacitor having one end connected to a portion of said first main line and the other end connected to said first stub, and having a low impedance with respect to a signal of a frequency band used and a high impedance, which provides a loss, with respect to a signal of a higher frequency band than the frequency band used; a second main line connected between an output terminal of said semiconductor amplifying element and a signal output terminal; a second stub formed close to said second main line; and a second variable-impedance circuit including at least one capacitor having one end connected to a portion of said second main line and the other end connected to said second stub, and having a low impedance with respect to the signal of the frequency band used and a high impedance, which provides a loss, with respect to a signal of a higher frequency band than the frequency band used.