Motorola Corporation

Kenneth I Ray

Gordon H Allen

A feedback circuit is provided between the output and the input of a lower transistor amplifier of a push-pull amplifier driver output stage to inhibit power supply transients as the amplifier output stage transitions rapidly from a low to high output state. Additionally, if the push-pull output stage is incorporated within a three state gate or the like, which gate shares a common bus with other like three state gates, the feedback circuit inhibits loading of the bus whenever the three state gate is operated in a three state mode or is powered down as the other gates are active and are rapidly transitioned between low and high output states. The feedback circuit provides a low impedance path at the input of the lower transistor amplifier of the push-pull driver output stage to shunt transient currents harmlessly away from the base thereof to prevent the transient currents from turning on the lower transistor amplifier.

Miller capacitance effect eliminator for use with a push-pull amplifier

A voltage reference circuit for producing a predetermined output voltage at an output thereof having good output voltage regulation and which includes a diode bias string and a transistor having its base-emitter path coupled via a diode between predetermined ones of the diodees comprising the diode bias string. The output of the voltage reference circuit is taken at the emitter of the transistor. The voltage reference circuit presents a low impedance at the output thereof and is capable of both sourcing and sinking current thereat over a wide range of current values.

Voltage reference circuit

A circuit for providing a control signal having a first predetermined magnitude in response to an analog voltage having a magnitude below a particular threshold and the control signal having a second predetermined magnitude in response to the magnitude of the analog voltage being above the particular threshold includes a threshold establishing circuit, a first transistor and a second transistor. The threshold establishing circuit receives the analog voltage and enables the first transistor to remain non-conductive until the analog voltage reaches the threshold. The second transistor is connected to the first transistor and to the analog voltage supply. The second transistor is arranged to be initially conductive as the magnitude of the analog voltage rises, and to become non-conductive in response to the first transistor being rendered conductive so that the desired control signal is developed at an output electrode of the second transistor.

Power-on reset circuit for monolithic I.C.'s

The bus terminating circuit isolates itself from a bus in response to the magnitude of a power supply voltage decreasing below a predetermined threshold level. The bus terminating circuit includes a bus termination voltage divider network having one terminal coupled through a threshold sensing device to one of the pair of power supply terminals, another terminal coupled to the bus and a further terminal coupled through a transistor to the other of the pair of power supply terminals. Another threshold sensing circuit is coupled between one of the pair of power supply terminals and the control electrode of the transistor. The threshold sensing circuits are responsive to the magnitude of the power supply voltage falling below the predetermined threshold level to render devices of the threshold sensing circuits non-conductive and thereby electrically isolate the bus termination network from the bus.

Bus terminating and decoupling circuit

An improved fall time is achieved in bipolar transistor logic circuits which have three-state outputs. The circuits comprise a logic input terminal which is coupled to a push-pull output stage to drive a three-state output terminal. A three-state input receives three-state control signals for holding the output transistors in their non-conducting, high impedance state. Improved speed is achieved by adding a feedback circuit to remove stored base charge from the upper output driver transistor and to supply base current derived from the load to the lower output driver transistor during high to low transitions of the output voltage.

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Mesa, AZ, United States of America

Kenneth I Ray