SU744927A1 - Pulse shaper - Google Patents

Description

The invention relates to radioelectronics and can be used in an information processing unit. A device consisting of a transformer, a reference element on three diodes and a master resistor, an input stage on an emitter repeat and an inverter chip transistor-transistor logic (TTL) ij is known. The input sinusoidal voltage is formed into rectangular pulses by limiting the TTL with the supervisor. Compensation for a nonzero opening threshold is achieved by reference diodes, the voltage on which is set from the power source through a resistor. The device does not have sufficient accuracy, since the duty cycle of the generated pulses depends on the reference voltage on the voltage of the power source, as well as on the technological variation of parameters of the supporting diodes. A device containing a threshold element — a Schmidt trigger with a voltage divider and feedback circuit is known. consisting of successively. an output pulse detector that smoothes RC -h {) Iltra and a regulating stage on a transistor, whose collector is connected & the divider of the threshold element, and the base to the output of RC-filter 2. The known device works as follows. The smoothing -filter emits a constant voltage, proportional to the constant component of the voltage of the rectified output pulse r. This voltage controls the current of the regulating transistor and, Sledov-1, the voltage of the input element of the threshold element. In this case, the trip response times change. Hera Shgushdt that compensates for the change in the duration of the output pulses. kanrzheni under the action of some; Destabilizing factors.

A disadvantage of the known device is that the duration of the output pulses depends on changes in the supply voltage. For example, when the supply voltage rises, the amplitude of the output, pulses and, consequently, the DC voltage at the output of the smoothing RP filter increases. The collector current of the control transistor increases and, consequently, the bias voltage at the input of the threshold device. The constant voltage at the output of the smoothing RC filter decreases, i.e. stabilized, however, the duration of the output pulses is reduced.

The aim of the invention is to stabilize the duration of the output pulses when the supply voltage changes.

To achieve this, and in a pulse pulse form containing a threshold element, such as a Schmidt trigger with a constant voltage divider, a feedback circuit consisting of series-connected output pulse detector, a smoothing RC filter and a regulating stage at the transistor whose collector connected to the divider of the threshold element, and the base to the output of the RC filter; an emitter repeater with a resistor divider of the direct voltage at the input is inserted; the emitter of the regulating cascade is connected to the output of the emitter repeater, and the emitter follower collector - with a common bus.

The drawing is shown with: 1 electrical circuit of the proposed pulse generator.

Pulse shaper contains

input divider on resistors 1 and 2, threshold element 3, razelitepny capacitor 4, detector 5 output pulses, smoothing RC-4 W1tr on resistor 6 and capacitor 7, reversing cascade on the transistor 8, the base of which is connected to the output of the RC filter, and the collector through a resistor 9 - to the input divider. The regulator transistor emitter is connected to the output of an amitter follower formed by resistor 1O, transistor 11c with a basic divider on resistors 12, 13 The shaper works as follows,

The smoothing RC filter has a constant component of the rectified output rectangular pulses. With

The effect of destabilizing factors, with the exception of changes in the supply voltage, changes the output voltage of the output pulses, changes the constant voltage at the output of the RC output, which causes a change in the collector current of the controlling transistor 8 and a slow change in the input offset of the threshold element. A change in bias leads to a reverse change in the duration of the output pulses, which is thus stabilized.

Changes in the supply voltage cause proportional changes in the amplitude of the output pulses, hence the constant voltage at the output of the R C filter changes. However, in proportion to the change in the supply voltage, the voltage at the emitter follower and on the emitter of the control transistor 8 changes. The values of the resistances of the resistors 1O, 12, 13 are chosen such that the voltage difference between the base-emitter and the control transistor remains unchanged when the supply voltage changes . Consequently, the collector current of the control transistor, the input input of the threshold element and the duration of the output pulses remain unchanged.

The output impedance of the emitter follower is quite small, so the change in the voltage at the emitter of the regulating transistor 8 depends only on the change in the supply voltage and does not depend on its emitter current.

Claims (2)

1. Author's certificate of the USSR NS 447821, cl, H 03 K 5/08, 1973. 2. USSR author's certificate number 416837, kp. H 03 K 3/295, 1972 (prototype).