Abstract: A differential amplifier includes two amplifier halves each including a feedback transistor for providing closed-loop gain, for driving a common load impedance, and for providing a differential current output. Each amplifier half further includes a first feedback path operable in a normal operating condition and a second feedback path operable in an overdrive condition. The first feedback path consists of first and second diodes connected between an emitter of the feedback transistor and a voltage input of the differential amplifier. A junction between the first and second diodes is coupled to the common load impedance. The second feedback path consists of a third diode connected between the emitter of the feedback transistor and the second voltage input, such that the differential amplifier and the feedback transistor remain operational and electrically isolated from the load impedance during the overdrive condition.

Abstract: Calibrated voltage cursors with respect to an input waveform signal are produced for display with the input waveform signal by injecting the cursor signals into the signal path prior to any gain stages in the signal path.

Abstract: A television picture on a television test and measurement instrument adds a vertical sweep generator, and if necessary a horizontal sweep generator, to a conventional instrument. Vertical and horizontal sweep triggers are generated by a sync processor of the instrument from an input video signal to drive the respective sweep generators. A vertical sweep signal from the vertical sweep generator is input to a switch together with the input video signal. The output of the switch drives a vertical deflection circuit such that when the input video signal is output from the switch the instrument is in standard waveform monitor mode, and when the vertical sweep signal is output from the switch the instrument is in a picture mode to provide a raster scan image of the input video signal on a display.

Abstract: A horizontal position control for a television waveform monitor includes a potentiometer that has a substantially linear input position/output voltage transfer function, and a circuit for reducing the sensitivity of the horizontal position control over a predetermined range of input positions of the potentiometer. The reduced sensitivity is preferably provided over a band approximately at the center of the range of horizontal positions covered by the horizontal position control.