Fast edge generator with wide dynamic range

#a. Field of the Invention

#The present invention relates to electronic calibration equipment for verifying the high frequency characteristics of electronic test equipment, including oscilloscopes and time interval analyzers.

#b. Related Art

#The invention will now be described by way of example, with reference to the accompanying drawings, in which:

#FIG. 1 is a schematic block diagram of a prior art electric circuit for generating an electronic fast edge waveform of selectable amplitude;

#FIG. 2 is a schematic block diagram of an electronic circuit according to the invention, for generating an electronic fast edge waveform of selectable amplitude, having five pairs of pulse generators of opposite polarity, each pulse generator being individually activatable; and

#FIG. 1 shows a schematic block diagram of a prior art electronic circuit 1 for generating an electronic fast edge waveform of selectable amplitude. This circuit 1 has an output 2 that can be connected via a suitable connector or coaxial line 3 to the input 4 of equipment under test, for example an oscilloscope (not shown). The circuit 1 comprises a pair of pulse generators 5, 6 of opposite polarity. Both pulse generators 5, 6 are connectable to positive and negative power supply rails 7, 8, and to an enable input (E) 47 to which is applied either a positive-going pulsed waveform 48 or a similar negative-going pulsed waveform 49. The pulsed waveforms 48, 49 have an adjustable frequency of between 10 Hz and 2 MHz with a 10% duty cycle. The rise and fall times of the pulsed waveforms is modest at about 1 ns.

#When both of the pulse generators 5, 6 are energised at the power rails 7, 8, either the positive-going waveform 48 or the negative-going waveform 49 is applied to the pulse generators 5, 6 via the enable input 47. One pulse generator 5 is only activated by the positive-going pulses, and the other pulse generator 6 is only activated by the negative-going pulses so that just one of the pulse generators 5, 6 is active at any time when either of the pulses 48, 49 is present at the enable input 47.

#The pulse generators each produce pulses at a pulse generator output 11, 12 that follow the input positive-going and negative-going pulses 48, 48, but with faster falling or rising edges 9, 10 with a speed of less than 100 ps. The voltage on the power rails 7, 8 can be varied to vary the dynamic range of the fast edge 9, 10 by about 10 dB. Each output 11, 12 is wired to a reverse-biased beam-lead silicon Schottky diode 13, 14.