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Pulse Shaping Circuit

IP.com Disclosure Number: IPCOM000083348D
Original Publication Date: 1975-May-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Hoyt, ES: AUTHOR

Abstract

This circuit using one diode bridge, two matched pairs of diodes, and four DC current sources is very stable, and provides independently controllable rise and fall time and positive and negative amplitude control over a wide range of frequencies and temperatures.

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Pulse Shaping Circuit

This circuit using one diode bridge, two matched pairs of diodes, and four DC current sources is very stable, and provides independently controllable rise and fall time and positive and negative amplitude control over a wide range of frequencies and temperatures.

Referring to the schematic, when the input node is at a low level all the current from current source CS1 is flowing through diode CR1, causing CR2 and CR5 to be reverse biased. CS3 is pulling current through CR6 and CR7 from CS4.

The same amount of current is also flowing through the CR8 from CS4 to the negative amplitude of adjusted supply. The current through CS4 is always set as twice the current through CS3. The voltage at capacitor C1 will be the same as the amplitude supply if CR7 and CR8 are matched properly.

When the input switches to the high-voltage state, CR5 starts conducting and CR6 and CR1 are reverse biased. The current then starts flowing from CS1 through CR2 into C1, which will charge at a rate determined by the current and the capacitor value of C1.

When the capacitor charges to the amplitude that the positive control has been set, CR3 will begin to conduct clamping the output voltage at C1 to that value. The current through CR3 and CR4 controls the positive amplitude in a manner similar to this. The diode drops will change at the same rate per degree, such that no change in amplitude is expected over a wide temperature range.

The excellent tracking characteristic...