04352152 is referenced by 4 patents and cites 6 patents.

Method and apparatus are disclosed herein for controlling the voltage supplied to a motor to vary the speed thereof. A pulsewidth modulator is supplied a sawtooth waveform from a waveform generator and is controlled by an input signal to provide a variable duty cycle pulse train. The waveform generator also provides a start pulse which triggers an output driver circuit. The output driver circuit provides base current to a plurality of paralleled output transistor stages, which may be Darlington pairs, connected to the motor. The collector voltage of the output stages is monitored and, if it drops below a predetermined threshold at the edge of saturation, is clamped to a voltage and the edge of saturation, thereby preventing the output transistors from operating in saturation while at the same time minimizing the voltage across the collector of the output stages. This arrangement eliminates the need for emitter resistors while at the same time providing for high speed operation and better load sharing among the paralleled output transistors.

Title
High speed non-saturating inverter
Application Number
6/111259
Publication Number
4352152
Application Date
January 11, 1980
Publication Date
September 28, 1982
Inventor
Stephen H Smith
Playa del Rey
CA, US
Agent
Lyon & Lyon
Assignee
Hybricon
CA, US
IPC
H02M 1/12
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