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A High-Speed, Glitch-Free Triangle Pulse Generator

IP.com Disclosure Number: IPCOM000041029D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Myers, W: AUTHOR

Abstract

The circuit of Fig 1 generates a fast triangular-shaped pulse either positive or negative polarity, with programmable slopes, and with complete freedom from switching noise at the peak of the pulse.

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A High-Speed, Glitch-Free Triangle Pulse Generator

The circuit of Fig 1 generates a fast triangular-shaped pulse either positive or negative polarity, with programmable slopes, and with complete freedom from switching noise at the peak of the pulse.

The desired results are achieved using a single high-speed current switch to control the charge current to a capacitor. Referring to Fig 1, the current-switching element is implemented using a high-speed transistor pair, T1 and T2, and is controlled by the differential input signal pair +IN and -IN. This switch controls the flow of I-, determining whether or not that current contributes, along with I+, to the charging of capacitor C. Both I+ and I- are digitally programmable. Diodes D1 and D2 are high-speed switching diodes and serve to limit the charge voltage across capacitor C to within a range from slightly higher than Vstop+ to slightly lower than Vstop-.

Referring to Fig 2, with +IN low, and assuming I- > I+, as would be the case for normal operation, the voltage across capacitor C is initially at the point determined by the conduction of diode D2. When +IN goes high, I+ charges capacitor C at the rate dVout/dt = I+ / C. When +IN goes back LOW, C discharges again at the rate dVout/dt = (I+ - I-) / C until Vout again reaches the point where diode D2 conducts. For an inverted triangle, the +IN pulse is simply inverted, with the positive and negative slopes of the resulting waveform defined by the same formulas as...