Tektronix, Inc.

Kenneth G Schlotzhauer

Arthur J Metz

Michael L Rieger

Carl R Battjes

Harvey Leon Golladay

Binoy Anthony Rosario

Stephen Anthony Roth

A programmable trigger coupling circuit and trigger circuit for selecting DC and AC coupling modes in addition to a few other coupling modes without using a DC blocking capacitor in series with the signal path. A short high frequency signal path, low pass filter network and a subtraction circuit are used for obtaining the basic trigger coupling modes. Additional circuits may be used for expanded coupling modes and functions.

Trigger coupling circuit for providing a plurality of coupling modes

The cascomp amplifier is modified to provide a dynamic biasing circuit which varies the bias point of the cascomp amplifier in proportion to the change in the true bias point of the main channel pair to allow full thermal V.sub.be error correction for overdrive conditions and for common-mode signals. A buffer amplifier senses the average voltage of the main channel input transistor emitters and generates a voltage proportional to this average which is added to the biasing network for the cascomp amplifier common-base amplifier transistors.

Overdrive thermal distortion compensation for a Quinn cascomp amplifier

A trigger circuit including arm and trigger comparators which are responsive to the push-pull output from a differential amplifier but insensitive to its common mode component. A controllable hysteresis insertion circuit is also included in the circuit for noise rejection and sensitivity control purposes.

Trigger circuit

A current-limiting circuit for a differential amplifier includes a voltage generator which is switched in parallel with a signal-current-generating impedance connected between the emitters of the differential amplifier transistors whenever an input signal exceeds the voltage of the voltage generator. A practical embodiment for limiting the current in either direction for opposite-polarity input signals includes a pair of voltage generators cross-coupled from a respective differential amplifier transistor base to the opposite transistor emitter via transistor switches.

Current-limiting mechanism for a precision differential amplifier

The cascode feed forward amplifier is modified to correct alpha-induced error. A pair of resistors are serially disposed between the bases of a pair of common-base amplifiers to generate an error voltage proportional to the input signal. The error voltage is applied to the correction amplifier to provide an appropriate correction current.

Cascode feed-forward amplifier

A circuit for accurately extracting the synchronization information contained within a composite video waveform includes a means for establishing the back porch level of the waveform to a first voltage through a first feedback loop, a means for establishing the sync tip level of the waveform to a second voltage through a second feedback loop, a means for providing the extracted synchronization information at a time determined midway between the first and second voltages, and a system which achieves these ends. An automatic gain control amplifier is included as a portion of the circuit within the system and whose gain is linearly proportional to the logarithm of the AGC voltage and wherein changes in AGC voltage do not interrupt the DC potentials within the amplifier nor do DC changes change the gain of the amplifier.

Circuit for accurately extracting the synchronization information

A circuit to correct for pincushion distortion and defocusing in a cathode-ray tube having electromagnetic deflection systems is disclosed. The circuit, which may be realized in monolithic integrated-circuit form, performs a mathematical function to predistort the deflection signal for each axis by the amount necessary to provide an undistorted display. The circuit also provides a signal to correct for the defocusing that occurs at the edges of the screen. The circuit may be readily adapted for use with cathode-ray tubes having different diagonal deflection angles, and with either flat of curved faceplates, by changing the values of two resistors.

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Beaverton, OR, United States of America

Kenneth G Schlotzhauer