| 摘要 |
An FET mixer circuit having a stable input impedance uses two tandem-connected GaAs MESFET's (1) and (2) of pulse doped structure instead of a conventional MESFET or a HEMT, as an active device. A gate biasing point for the FET (1) is set around a pinch-off point of a mutual conductance, and a gate biasing point for the FET (2) is set in a region which assures non-change of a mutual conductance with respect to the increase of a gate voltage. Thus, a mixer circuit having a good isolation characteristic for an RF signal and a local oscillation signal and exhibits substantially no change in the input impedance is attained.
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