A HIGH SPEED TUNNEL DIODE DECADE SCALER
Date
1963
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Degree Level
Doctoral
Abstract
The thesis describes in detail the design and operation of a fast tunnel diode decade scaler which can operate up to a frequency of about 25 Mc/s. The scaler has wide tolerance for the d.c. biasing currents in the tunnel diodes and for the input pulse amplitude. It is found that not more than 8 tunnel diodes can be used in a single chain, if good reliability of operation with wide tolerance for the d.c. biasing currents and input pulse amplitude is to be achieved. Hence, the decade scaler is formed by a scale of 5 followed by a scale of 2.
Since the pulses to be counted may have varying amplitudes and pulse widths, it is necessary to standardise them before feeding to the scaler unit. This is done by an input circuit discriminator which is based on a tunnel diode monostable multivibrator. The tunnel diode univibrator
described here has a resolution of 0.1 μs and the results indicate that the speed could be improved by the use of faster tunnel diodes.
Both positive and negative output pulses of 0.5 v amplitude may be taken from the output circuit. These may be used as the input pulses to existing fast counters or else to a similar decade scaler. Thus, the complete unit described may be used as an input stage to existing fast
counters.
During the study of the resolution of the counter, it was found that a special multipulse generator was required, and it was designed and constructed. This generator is capable of supplying four independent pulses, or a train of four pulses, with a rise time of 3 nsecs. The width of each pulse may be independently and continuously varied from 5 to 100 nsecs. Also, the position of each pulse may be continuously and independently varied with respect to a
synchronising edge. The generator can deliver positive or negative pulses with a maximum
amplitude of 2 v into an impedance of 50 ohms.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Electrical and Computer Engineering
Program
Electrical Engineering