Mixer circuit

Claim 2

A mixer circuit for mixing a radio frequency signal and a local oscillation signal to output an intermediate frequency signal comprising: a radio frequency signal input terminal to be supplied with the radio frequency signal, a local oscillation signal input terminal to be supplied with the local oscillation signal, an intermediate frequency signal output terminal for outputting the intermediate frequency signal, a first field effect transistor with a pulse-doped structure, for mixing the radio frequency signal and the local oscillation signal from said input terminals to output the intermediate frequency signal, said first field effect transistor being a dual gate field effect transistor and having a first gate, a second gate connected to said radio frequency input terminal, a drain connected to said intermediate frequency signal output terminal, and a source connected to a voltage potential, and second field effect transistor with pulse-doped structure, said second field effect transistor being a single gate field effect transistor and having a gate connected to said local oscillation signal input terminal, said gate of said second field effect transistor having a shorter gate width than said first gate of said first field effect transistor, a drain connected to said first gate of said first field effect transistor, and a source connected to said voltage potential.

Claim 3

The mixer circuit as claimed in claim 1, wherein said mixer includes: first bias means for supplying said first gate of said first field effect transistor with a gate bias voltage in the vicinity of a pinch-off voltage of said first gate; second bias means for supplying said second gate of said first field effect transistor with a gate bias voltage such that a mutual conductance of said second gate is unvaried even when a gate input voltage of said second gate is varied; and third bias means for supplying said gate of said second field effect transistor with a gate bias voltage such that a mutual conductance of said gate of said second field effect transistor is unvaried even when a gate input voltage of said gate of said second field effect transistor is varied.

Claim 4

The mixer circuit as claimed in claim 2, wherein said second field effect transistor is a GaAs-MESFET having a pulse-doped structure.

Claim 5

The mixer circuit as claimed in claim 3, further including a coupling capacitor disposed between said drain of said second field effect transistor and said first gate of said first field effect transistor.

Claim 6

The mixer circuit as claimed in claim 4, further including a matching circuit, disposed between said second gate of said first field effect transistor and said radio frequency signal input terminal, for matching an input impedance of said second gate.

Claim 7

The mixer circuit as claimed in claim 5, further including a low-pass filter between said drain of said first field effect transistor and said intermediate frequency signal output terminal.

Claim 8

The mixer circuit as claimed in claim 6, further including a filter, disposed between said gate of said second field effect transistor and said local oscillation signal input terminal, for preventing the intermediate frequency signal mixed-down in said mixer circuit from leaking to an opposite side of said local oscillation signal input terminal.

Claim 9

A mixer circuit for mixing a radio frequency signal and a local oscillation signal to output an intermediate frequency signal comprising: a radio frequency signal input terminal to be supplied with the radio frequency signal, a local oscillation signal input terminal to be supplied with the local oscillation signal, an intermediate frequency signal output terminal for outputting the intermediate frequency signal, a first field effect transistor with a pulse-doped structure, for mixing the radio frequency signal and the local oscillation signal from said input terminals to output the intermediate frequency signal, said first field effect transistor being a dual gate field effect transistor and having a first gate connected to said local oscillation signal input terminal a second gate, a drain connected to said intermediate frequency signal output terminal, and a source connected to a voltage potential, and a second field effect transistor with a pulse-doped structure, said second field effect transistor being a single gate field effect transistor and having a gate connected to said radio frequency input terminal, said gate of said second field effect transistor having a gate width shorter than said second gate of said first field effect transistor, a drain connected to said second gate of said first field effect transistor, and a source connected to said voltage potential.

Claim 10

A mixer circuit for mixing a radio frequency signal and a local oscillation signal to output an intermediate frequency signal comprising: a radio frequency signal input terminal to be supplied with the radio frequency signal, a local oscillation signal input terminal to be supplied with the local oscillation signal, an intermediate frequency signal output terminal for outputting the intermediate frequency signal, a first field effect transistor with a pulse-doped structure, for mixing the radio frequency signal and the local oscillation signal from said input terminals to output the intermediate frequency signal, said first field effect transistor being a dual gate field effect transistor and having a first gate connected to said local oscillation signal input terminal a second gate, a drain connected to said intermediate frequency signal output terminal, and a source connected to a voltage potential, and a second field effect transistor with a pulse-doped structure, said second field effect transistor being a single gate field effect transistor and having a gate connected to said radio frequency input terminal, said gate of said second field effect transistor having a gate width shorter than said second gate of said first field effect transistor, a drain connected to said second gate of said first field effect transistor, and a source connected to said voltage potential.

Claim 11

The mixer circuit as claimed in claim 8, wherein said mixer circuit includes: first bias means for supplying said first gate of said first field effect transistor with a gate bias voltage in the vicinity of a pinch-off voltage of said first gate; second bias means for supplying said second gate of said first field effect transistor with a gate bias voltage in the vicinity of a pinch-off voltage of said second gate; and third bias means for supplying a gate of said second field effect transistor with a gate bias voltage such that a mutual conductance of said gate of said second field effect transistor is unvaried even when a gate input voltage of said gate of said second field effect transistor is varied.

Claim 12

The mixer circuit as claimed in claim 9, wherein said second field effect transistor is a GaAs-MESFET.

Claim 13

The mixer circuit as claimed in claim 10, further including a coupling capacitor disposed between said drain of said second field effect transistor and said second gate of said first field effect transistor.

Claim 14

The mixer circuit as claimed in claim 11, further including a matching circuit, disposed between said gate of said second field effect transistor and said radio frequency signal input terminal, for matching an input impedance of said gate of said second field effect transistor.

Claim 15

The mixer circuit as claimed in claim 12, further including a low-pass filter disposed between said drain of said first field effect transistor and said intermediate frequency signal output terminal.

Claim 16

The mixer circuit as claimed in claim 13, further including a filter, disposed between said first gate of said first field effect transistor and said local oscillation signal input terminal, for preventing the intermediate frequency signal mixed-down in said mixer circuit from leaking to an opposite side of said local oscillation signal input terminal.

Claim 17

A mixer circuit for mixing a radio frequency signal and a local oscillation signal to output an intermediate frequency signal comprising: a radio frequency signal input terminal to be supplied with the radio frequency signal, a local oscillation signal input terminal to be supplied with the local oscillation signal, an intermediate frequency signal output terminal for outputting the intermediate frequency signal, a first field effect transistor with a pulse-doped structure, for mixing the radio frequency signal and the local oscillation signal from said input terminals to output the intermediate frequency signal, said first field effect transistor being a dual gate field effect transistor and having a first gate, a second gate, a drain connected to said intermediate frequency signal output terminal, and a source connected to a voltage potential, a second field effect transistor with a pulse-doped structure, said second field effect transistor being a single gate field effect transistor and having, a gate connected to said local oscillation signal input terminal, said gate of said second field effect transistor having a shorter gate width than said gate of said first field effect transistor, a drain connected to said first gate of said first field effect transistor, and a source connected to said voltage potential, and a third field effect transistor with a pulse-doped structure, said third effect transistor being a single gate field effect transistor and having, a gate connected to said radio frequency signal input terminal, said gate of said third field effect transistor having a shorter gate width than said gate of said first field effect transistor, a drain connected to said second gate of said first field effect transistor, and a source connected to said voltage potential.

Claim 18

A mixer circuit for mixing a radio frequency signal and a local oscillation signal to output an intermediate frequency signal comprising: a radio frequency signal input terminal to be supplied with the radio frequency signal, a local oscillation signal input terminal to be supplied with the local oscillation signal, an intermediate frequency signal output terminal for outputting the intermediate frequency signal, a first field effect transistor with a pulse-doped structure, for mixing the radio frequency signal and the local oscillation signal from said input terminals to output the intermediate frequency signal, said first field effect transistor being a dual gate field effect transistor and having a first gate, a second gate, a drain connected to said intermediate frequency signal output terminal, and a source connected to a voltage potential, a second field effect transistor with a pulse-doped structure, said second field effect transistor being a single gate field effect transistor and having, a gate connected to said local oscillation signal input terminal, said gate of said second field effect transistor having a shorter gate width than said gate of said first field effect transistor, a drain connected to said first gate of said first field effect transistor, and a source connected to said voltage potential, and a third field effect transistor with a pulse-doped structure, said third effect transistor being a single gate field effect transistor and having, a gate connected to said radio frequency signal input terminal, said gate of said third field effect transistor having a shorter gate width than said gate of said first field effect transistor, a drain connected to said second gate of said first field effect transistor, and a source connected to said voltage potential.

Claim 19

The mixer circuit as claimed in claim 15, wherein said mixer circuit includes: first bias means for supplying said first gate of said first field effect transistor with a gate bias voltage in the vicinity of a pinch-off voltage of said first gate; second bias means for supplying said second gate of said first field effect transistor with a gate bias voltage in the vicinity of a pinch-off voltage of said second gate; third bias means for supplying said gate of said second field effect transistor with a gate bias voltage such that a mutual conductance of said gate of said second field effect transistor is unvaried even when a gate input voltage of said gate of said second field effect transistor is varied; and fourth bias means for supplying a gate of said third field effect transistor with a gate bias voltage such that a mutual conductance of said gate of said third field effect transistor is unvaried even when a gate input voltage of said gate of said third field effect transistor is varied.

Claim 20

The mixer circuit as claimed in claim 16, wherein each of said second field effect transistor and said third field effect transistor is a GaAs-MESFET having a pulse-doped structure.

Claim 21

The mixer circuit as claimed in claim 17, further including a first coupling capacitor disposed between said drain of said second field effect transistor and said first gate of said first field effect transistor, and a second coupling capacitor disposed between said drain of said third field effect transistor and said second gate of said first field effect transistor.

Claim 22

The mixer circuit as claimed in claim 18, further including a matching circuit, disposed between said gate of said third field effect transistor and said radio frequency signal input terminal, for performing an input impedance matching operation for said gate of said third field effect transistor.

Claim 23

The mixer circuit as claimed in claim 19, further including a low-pass filter disposed between said drain of said first field effect transistor and said intermediate frequency signal output terminal.

Claim 24

The mixer circuit as claimed in claim 20, further including a filter, disposed between said gate of said second field effect transistor and said local oscillation signal input terminal, for preventing the intermediate frequency signal mixed-down in said mixer circuit from leaking to an opposite side of said local oscillation signal input terminal.