AMPLIFIER SYSTEMS AND FET MODULATION

专利名称：AMPLIFIER SYSTEMS AND FET

MODULATION

发明人：MARTIN J. MORGAN,WILLIAM C.

EVANS,RICHARD A. RAPPAPORT,ALFRED N.GUTZMER

申请号：US3559107D申请日：19671009公开号：US3559107A公开日：19710126

摘要：A direct current voltage is applied to the gate electrode of an FET (field effecttransistor) to modulate a carrier passing through the FET between its drain and sourceelectrode. The carrier is an alternating current from a fixed amplitude source. Theresistance between drain and source of the FET varies in accordance with the amplitudeof the modulating voltage, hence, the carrier becomes amplitude modulated thereby.Bias voltage is applied to the FET's gate electrode at the value required for zerotemperature coefficient operation of the transistor. Variation in the net gate bias due tothe modulating voltage is substantially prevented by negative feedback of the amplifiedand demodulated carrier voltage to the gate electrode. Further temperature

compensation is provided by a zener diode made of the same semi-conductor material asthe FET and incorporated in the supply of bias voltage. The bias voltage for zerotemperature coefficient operation is determined by means of the relation RdsGm= K,where Rds is the value of the FET's drain-source resistance at the zero temperaturecoefficient point, Gm is the FET's forward transfer transconductance and K is a constant

having the value of about 0.184.

申请人：SYBRON CORP.

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