Abstract: An operational power amplifier having a bootstrap power output stage is designed to provide maximum dynamic range over a wide range of supply voltages. A control circuit in the form of a switched current mirror is added to the amplifier biasing circuit. At supply voltage higher than a predetermined threshold, the amplifier bias is adjusted to provide one half of this voltage at the output terminal. For supply voltages less than the threshold value, the output voltage is made less than half supply voltage.

Abstract: In an integrated circuit audio power amplifier a 6 db per octave frequency-gain roll off is obtained in a conventional manner by converting a high gain inverter to an integrator and driving the integrator from a current source. A second cascaded stage is also provided so that it operates at lower gain and has a matching high frequency roll off. When such characteristics are combined in cascade the result is a 12 db per octave roll off at the higher frequencies. A flat negative feedback loop is employed to maintain a controlled constant low frequency gain. In the response region located between the 12 db per octave slope region and the constant gain region there is a 6 db per octave slope. The configuration is stable without resorting to frequency sensitive feedback.

Abstract: A diode connected transistor acts as a current mirror input stage with the input current source acting as a shunt for the diode. The input stage is coupled to a complementary composite output transistor pair which supplies an output current that mirrors the input current. Since the input shunts the diode, the input potential can approach the supply rail to within substantially less than one V.sub.BE.

Abstract: An audio power amplifier is designed to have a wide band high fidelity response suitable for FM radio performance. The amplifier rolloff of gain versus frequency is made sufficiently steep to reduce the gain to a negligible level at the standard AM broadcast band. A stabilization network is incorporated into the amplifier to avoid instabilities that might result in oscillation. The amplifier has a very low AM broadcast band radiation so that it is useful in AM-FM radio receivers.