| 摘要 |
A radio frequency amplifier having a power transistor (Q1) to the base of which is coupled a radio frequency signal to be amplified. An amplified radio frequency signal is provided at the collector of the power transistor (Q1). A control transistor (Qc) has its base coupled to the base of the power transistor (Q1) whilst a driver transistor (Q2) provides a control bias signal to the bases of the control and power transistors. A differential amplifier (Qd1, Qd2) has a first input coupled to an input bias signal and an output coupled to the base of the driver transistor (Q2). The collector of the control transistor (Qc) is coupled to a second input of the differential amplifier to provide a negative feedback signal to the differential amplifier and the driver transistor (Q2) and thereby to stabilise the operating point of the power transistor (Q1). |
