Abstract: An amplifier circuit includes a bias control feedback loop. A sensing transistor (105) is matched to one or more power transistors (101a, 101b, 101c) and is correspondingly biased. The difference between collector voltage of the sensing transistor (105) and a reference voltage amplified by a differential amplifier (111, 114) provides the base bias voltage for the power transistors (101a, 101b, 101c) and the sensing transistor (105). The gain of the amplifier is controlled by applying a control voltage to a resistor (110) connected to the collector of the sensing transistor (105).

Abstract: The present invention relates to a circuitry for impedance matching. The invention utilizes circuitry for impedance matching, which circuitry for example is connected to a differential or balanced power amplifier or some other device in need of output impedance tuning. The circuitry includes at least one inductance connected to at least one device which conducts when being forward biased, and a direct current (DC) source controlling the conduction of the device. The circuitry eliminates the DC component of a signal passing through it. By controlling the device that is conducting when it is forward biased, it is possible to turn the circuitry on and off, thus altering the impedance at the output of the amplifier. Hence, a load switch has been created at the output of the amplifier.

Abstract: The present invention relates to a circuitry for impedance matching. The invention utilizes circuitry for impedance matching, which circuitry for example is connected to a differential or balanced power amplifier or some other device in need of output impedance tuning. The circuitry includes at least one inductance connected to at least one device which conducts when being forward biased, and a direct current (DC) source controlling the conduction of the device. The circuitry eliminates the DC component of a signal passing through it. By controlling the device that is conducting when it is forward biased, it is possible to turn the circuitry on and off, thus altering the impedance at the output of the amplifier. Hence, a load switch has been created at the output of the amplifier.

Abstract: An amplifier circuit includes a bias control feedback loop. A sensing transistor (108) is matched to one or more power transistors (101a, 101b, 101c) and is correspondingly biased. The difference between collector voltage of the sensing transistor (108) and a reference voltage amplified by a differential amplifier (111, 114) to provide the base bias voltage for the power transistors (101a, 101b, 101c) and the sensing transistor (105). The gain of the amplifier is controlled by applying a control voltage to a resistor (110) connected to the collector of the sensing transistor (105).