RF Amplifier having automatic gate bias switching in response to band selection
AssigneeAlps Electric Co., Ltd.
InventorSadayoshi Ijichi
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Abstract
Herein disclosed is an RF amplifier which is equipped with a high-frequency amplifying element such as a dual gate MOS FET having its first gate fed with a bias voltage and its second gate fed with an AGC voltage, in which a switching diode is fed with a switching voltage thereby to switch the bands, in which the voltage at a voltage dividing point where the switching voltage is divided is used as the bias voltage, and in which the voltage at the dividing point is so raised upon the reception of a high band as to make the effect of the AGC uniform upon the receptions of the low and high bands.
Claims5
An RF amplifier of the type equipped with a dual gate MOS FET, comprising:
- input means receptive to frequencies of high and low bands;
- selecting means for feeding the first gate of said FET selectively with either frequencies in said high band or frequencies in said low band;
- means for feeding the second gate of said FET with an automatic gain control (AGC) voltage;
- and
- means for feeding the first gate of said FET with a bias voltage differing in accordance with the selecting of either said high or said low band.
Dependencies are inferred from the claim text.