PURPOSE: To control externally a bias voltage, by connecting a heatsensing element in series with a constant voltage source in a bias circuit and controlling the heat of a heater arranged near the heat-sensing element.
CONSTITUTION: The heat-sensing element 6 the electric characteristic of which is changed with temperature is connected in series with the constant voltage circuit 4 of the bias circuit, and the heater 7 whose heat is controlled externally is arranged near the heat-sensing element. An idling current ICQ of the power amplification circuit like this is expressed in equation, where VB is a bias voltage, and when the bias voltage VB is changed, the idling current ICQ is changed naturally. The bias voltage VB is expressed as VB=Vb+VT, where Vb is a voltage of the constant voltage power supply and VT is a voltage drop of the element 6. When the Vb is constant, the variation of the VT is the variation of the VB, then the bias voltage VB is varied by changing the VT. The VT is changed by heatng the element with the heater 7.
JIKOU HIDEYASU
HIGASHIYAMA KATSUHIKO
TODA KAZUO
MATSUBARA SHIZUYOSHI
FUJII TAKASHI
