SU1525895A1 - Shaper of square light pulses - Google Patents

Abstract

The invention relates to a pulse technique and can be used as a transmitter of light signals through a fiber-optic communication line. The purpose of the invention is to increase speed by increasing the steepness of the fronts. When a paraphase signal appears on the forward output of the shaper 4, the logical zero signal of the LED 1 is added up from the collector current of the transistor 2 and the flowing current of the forward output of the shaper 4. At the same time, the forced current value of the LED 1 is due to the charging current of the capacitors 10,11. When switching the driver 4, the transistor 2 closes, and the open transistor 3 shunts the transition of the LED 1, providing a high slope of the light pulse. The increase in the steepness of the front and the cut of the light pulse being formed is carried out without increasing the current consumption in the static mode. 1 il.

Description

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The invention relates to a pulse technique and can be used as a transmitter of light signals through a fiber-optic communication line.

The purpose of the invention is to increase the speed of the driver by increasing the steepness of the fronts.

The drawing shows a structural diagram of the former.

The driver contains a LED 1, transistors 2 and 3 pn-type, driver 4 paraphasic signals, resistors 5-7, diodes 8 and 9, capacitors 10 and 11.

The input of the driver 4 paraphase signals connected to the input terminal of the driver. The inverse output is connected to the base of transistor 2. The direct output is connected through parallel-connected resistor 6 and capacitor 11 to the cathode of diode 9 and through capacitor 10 to the base of transistor 3. The emitter of transistor 2 is connected via resistor 5 to a common bus. The collector is connected to the anode of the diode 9, the cathode of the LED 1, the anode of the diode 8, the emitter of the transistor 3, and through a resistor 7 to the base of the transistor 3 and the cathode of the diode 8, the collector of the transistor 3 and the power line.

The shaper works as follows.

In the static state with a voltage of 1 at the input of the former 4 paraphase signals with standard TTL input and outputs, a low voltage is present at the inverse output and a high voltage at the direct output. Transistors 2 and 3 are closed. There is no inflowing current from the direct output of driver 4. Consequently, there is no current through LED 1 and there is no luminescence. When the state at the input of the former 4 is changed, the state at its outputs also changes: at the inverse output, the state is high, and at the forward state, low. Transistor 2 opens and a current flows through it, determined by the voltage at its base and a resistor value of 5o. At the same time, the current of LED 1 is the sum of the collector current of transistor 2 and the current flowing into the forward output of the driver 4, which is the sum of the current flowing through the circuit m: LED 1 - diode 8 - capacitor 10

and LED 1 - diode 9 - parallel connected resistor 6 and capacitor 1 1 o

Resistor 7 serves to protect the transistor 3 and has a large nominal value. Therefore, the current through the resistor 7 can be neglected. The component of the current of LED 1 through capacitors 10 and 11 is limited by the resistances of the pn junction of LED 1 and diodes 8 and 9 and for the duration of the charge of capacitors 10 and 11 is the main part of the current through LED 1 The current through the LED 1 causes it to glow, and the initial current pulse, which exceeds the current in the static state, reduces the rise time of the light pulse with. At the end of the charge

capacitors 10 and 11 LED current

1 is added to the current flow

direct output of shaper 4 through

diode 9 and resistor 6 and collector current of transistor 2. Transistor 3 is closed, because the flowing current of the forward output of the driver 4 through diode 8 at the first time creates a negative bias at its base, and after the charge of the capacitor 10 terminates, the potentials at the base and emitter transistor 3 becomes equal.

When the state of the former 4 is changed, the voltage is set to the high level at the direct output, and low at the inverse output. The following occurs: the transistor 2 closes, the current of the direct output of the driver 4 stops. At the same time, turning the voltage on the direct output causes this voltage, flowing through the capacitor 10 to the base of the transistor 3, to open it and transfer it to the saturated mode with a shift of the base – emitter and base collectors in the forward direction. Opening transistor 3 leads to a sharp increase in voltage on the cathode of LED 1 and to the appearance of a path for current from the cathode to the anode of LED 1 through transistor 3. This leads to an accelerated discharge of the charge accumulated by LED 1 and a decrease in the time of the light pulse A diode 9 serves to eliminate the effect of the discharge current of the capacitor 11 on this process.

Claims (1)

The shaper may operate as a fast light shaper for transmitting them through a fiber optic link. A decrease in the rise and fall times of the light signal by a factor of 2-4 (to less than 10 n) is achieved practically without an increase in the power dissipation. Invention Formula A rectangular light pulse shaper comprising a pnp type first transistor, the emitter of which is connected via a first resistor to a common bus, an LED whose anode is connected to a power bus, an LED cathode is connected to a collector of the first transistor, characterized in that the purpose of improving the speed of the driver by increasing the steepness of the fronts. Editor I. Casarda Tehred L. Oliynyk Order 7242/54 Circulation 884 Subscription VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 paraphase driver, first and second diodes, second pnp transistor, first and second capacitors, second and third resistors, input of para-phase signal generator connected to the input terminal of the imager, direct output connected through the second resistor and the first capacitor connected in parallel with the cathode of the first diode and through the second capacitor with the base of the second transistor, the inverse output of the paraphase signal generator 5 is connected to the base of the first transistor, the anode of the first diode is connected to the collector of the first transistor, the anode of the second diode, the emitter of the second transistor and through the third 0 resistor - with the base of the second transistor and the cathode of the second diode, the collector of the second transistor is connected to the power bus. Proofreader S. Cherni