Base bias circuit, and power amplifier using the base bias circuit

摘要

A base bias circuit (1) operates like a constant voltage source, and a base bias voltage generated thereby varies according to fluctuation of the environment temperature without being influenced by the supply voltage, to hold a collector bias voltage constant. The base bias circuit (1) has a function of controlling the base bias voltage according to a control signal coming from the outside. By using a resistor (6) and resistor (14) having suitable resistances, the bipolar transistors constituting the bias circuit (1) can be small in size to reduce the electric current consumed by the bias circuit (1) thereby to make unnecessary the RF choke inductor between a power transistor (13) and the bias circuit (1). In short, the cost is lowered by making the chip size small and by reducing the number of external parts.