Tektronix, Inc.

Thomas P Dagostino

Luis J Navarro

Arnold M Frisch

Bruce E Miller

Roydn Jones

John D Trudel

A programmable analog multi-channel probe system is embedded within a device under test for coupling test points to external measurement points of the device under test. Programmable input buffer amplifiers are coupled to the test points to couple the data at those points to their outputs when enabled. The data from the input buffer amplifiers are input to respective routers to provide a plurality of outputs. Each common output from the routers is coupled as an input to an output buffer amplifier that provides the data as an output when enabled. The data at the output of the output buffer amplifiers is converted to a differential signal for transmission to the external measurement point by differential input/output amplifiers that have a reference level, selected from a plurality of reference levels including an internal reference level, as an input for comparison with the data from the output buffer amplifiers. A termination circuit may be provided for each output to provide appropriate impedance interface with the measurement points.

Analog multi-channel probe system

A charge coupled device (CCD) with separately addressable input signal gates is operated in the potential equilibrium mode. With properly selected voltage potentials the CCD can be used as a high speed linear detector of a variable analog signal without the need of preceeding independent sample and hold or peak detector circuits. The result is the efficient minimum/maximum detection of an analog signal in a fast-in/slow-out digitizer.

Method for using a charge coupled device as a peak detector

A waveform storage and display system particularly useful in digital oscilloscopes is provided in which successive waveforms of a repetitive signal are compared with a reference waveform, and upon detection of a difference or change within the waveform, the changed waveform is automatically stored. In addition to the conventional acquisition and display waveform memories, a reference-waveform and a changed-waveform memories are provided. Once a reference waveform is selected and stored, comparison of subsequent successive waveforms to detect changes is achieved under microprocessor control. Several display modes to provide a visual indication of changes may be implemented.

Waveform storage and display system

A digital oscilloscope is provided with a position control circuit which permits positioning of a signal both before and after digitizing. A track and hold circuit is coupled to the position control potentiometer to generate a reference voltage which tracks the position voltage in a waveform acquisition mode, and which is held at a fixed level in a display mode while the position voltage, which is applied to the acquisition preamp, is variable adjustable. A summation circuit subtracts the reference voltage from the position voltage to provide an altered positioning voltage for the display amplifier which is zero in the acquisition mode and variable in the display mode.

Position control circuit for a digital oscilloscope

A waveform storage system is provided in which waveform envelopes or maximum signal deviations along a waveform are detected and stored. A sampling clock operates at a predetermined fixed rate independently of a recording clock which is operable at rates determined by the sweep speed and is equal to or slower than the sampling clock. Data from an analog-to-digital converter is simultaneously applied to at least one latch and at least one comparator to be compared with the latch output. If the absolute value of the signal is greater than that stored in the latch, the latch is updated with the new value. The contents of the latch are clocked into memory by the recording clock.

Waveform storage system

A display system for a digital oscilloscope includes an interpolator for interpolating between stored waveform samples and providing additional samples at the interpolated values to thereby increase dot density of the resulting display.

Display interpolator employing a transversal filter for a digital

Jitter due to sample uncertainty in a digital oscilloscope is reduced by horizontally shifting each frame of a repetitive waveform display to provide an apparent time coincidence of each frame. The time interval between a fixed point on the successive waveforms and the next succeeding clock edge is measured, and a correction voltage is produced to offset the sweep voltage by the corrected amount.

Digital oscilloscope with reduced jitter due to sample uncertainty

A signal-envelope display system for a digital oscilloscope includes a memory for storing minimum and maximum signal values in adjacent storage locations, an address counter for sequentially addressing the memory, and a control circuit for selecting the least significant bit of the address count signal arriving at the memory from the least significant bit of the address count signal, a fixed logical low, or a fixed logical high to there by select every address location of the memory, or only the even locations, or only the odd locations over a given count cycle. The values retrieved from memory are converted to analog values and a vector generator connects the analog values to provide connected minimum and maximum values, connected maximum values, and connected minimum values for display. A signal-envelope display is provided by superposing the three displays.

Signal-envelope display system for a digital oscilloscope

A digital oscilloscope is provided with a display system which permits intensified time dots to be positionable between samples on a displayed waveform. The display system has a time dot memory having at least twice the number of addressable storage locations as a waveform memory. An address counter drives the time dot memory and the waveform memory, with time dot memory address count including one or more lesser significant bits than the waveform memory address count. The resolution of the time measurement provided by one or more time dots may be increased by increasing the time dot memory space and adjusting the corresponding number of address count bits to clock the memory at the commensurately higher rate.

Time dot display for a digital oscilloscope

A system for storing waveforms in which each waveform is converted to digital data and stored in a memory sector under the control of a history controller to select the sector and memory counter to select the individual address locations in each sector. When the memory capacity is exceeded, the oldest waveform data is replaced by the newest.

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Beaverton, OR, United States of America

Thomas P Dagostino