A class B push-pull amplifier has an output stage formed of two transistors having their connector-emitter paths connected in a series path across a direct voltage source. The transistors are controlled by a driver transistor which is supplied via an additional transistor having a resistance connected in series with its emitter. A further transistor having its base-emitter path connected across this resistance is so arranged and controlled that variations in the voltage of the voltage source have little or no effect on the current through the series path linking the transistors of the output stage.
A constant current drive circuit that can be driven directly from the output of a shift register which can find use, for example, in maintaining a constant current through a controlled device such as one or more light emitting diodes (LEDs) to ensure uniform brightness throughout a display surface that includes a plurality of LEDs.
A constant current drive circuit that can be driven directly from the output of a shift register which can find use, for example, as a constant current source for a light emitting diode (LED) to ensure uniform birghtness throughout a display surface that includes a plurality of LEDs.
First and second direct-coupled cascade connections of like numbers of transistors of the same conductivity type are connected in push-pull. The output stages have common-emitter and common-collector-amplifier transistors, respectively, while earlier stages have common-collector and common-emitter-amplifier transistors, respectively, the common-emitter-amplifier transistor working into a constant current generator collector load.
An output circuit, for minimizing output idle current fluctuations and improve the output voltage range, has first and second transistors connected to first and second power sources, with a plurality of diodes connected to control terminals of the first and second transistors. The output circuit further includes a third transistor having a first terminal connected to the second power source and a second terminal connected to a predetermined position among the plurality of diodes. A predetermined voltage is applied from the diodes to the control terminal of the first transistor when the third transistor is saturated, to bring a level of an output of said output circuit close to a level of the second power source. A fourth transistor, a fifth transistor, a first resistor, and a capacitor are also provided. The forth transistor has a control terminal connected to an output of a differential circuit, and a first terminal connected to the second power source through the first resistor as well as to the control terminals of the third and fifth transistors. A second terminal is connected to the first power source, with the fifth transistor having a first terminal connected to the second power source and a second terminal connected to the control terminal of the second transistor. The capacitor is connected between the control terminal of the fourth transistor and the second terminal of the fifth transistor. This output circuit also limits the output voltage without changing the impedance of the high-impedance input.
