CN204442308U - A kind of nothing divides gear to switch the quick edge pulse generating circuit of the program-controlled amplitude of link - Google Patents

Abstract

The utility model discloses a fast edge pulse generating circuit with a program-controlled amplitude without step-shift switching links, which comprises a triode pulse drive circuit, and a control input terminal of the triode drive circuit is connected with a trigger pulse input signal; the triode drive circuit includes Two triodes, the two triodes are PNP junction and NPN junction respectively, the collectors of the two triodes are connected as pulse output terminals, the bases of the two triodes are the control input terminals, and the two control input terminals are connected with the trigger A DC blocking coupling capacitor is respectively connected between the pulse input signals, and a DC power supply is alternately connected between the base and the emitter of the two triodes through a switch, and the DC power supply is used to set the pulse output terminal to reset state. The utility model reduces the rising and falling time of pulses through the addition of coupling capacitors and additional DC power sources, and can realize bidirectional output pulses according to input signals.

Description

A Fast Edge Pulse Generating Circuit with Programmable Amplitude Without Stepping Switching Link

technical field

The utility model belongs to the field of electronic circuits. In particular, it relates to a fast edge pulse generating circuit with programmable amplitude without step-shift switching link. The circuit has the following characteristics: sinking and pulling current drive capability not less than 0.5A, fast rising and falling pulse edges not greater than 10nS, no step-by-step switching link, programmable pulse amplitude and high and low levels can be set separately.

Background technique

According to the national regulations on the measurement and testing methods of electronic components parameters, the reverse recovery time Trr of low-power signal diodes, the delay time Td, rise time Tr, storage time Ts, fall time of optocouplers, bipolar transistors, and field effect transistors Time parameters such as time Tf, turn-on time Ton, and turn-off time Toff need to be tested as important indicators for evaluating component characteristics. In the test method, it is also clearly mentioned that the above parameters should be tested, as shown in Figure 1, it is necessary to use a fast edge pulse generator circuit as the excitation source.

As shown in Figure 2 in the traditional test circuit, a fast edge pulse generating circuit with a certain current load capacity can be made in the form of a class D amplifier circuit with a DC coupling structure. When the input signal is high, the lower transistor Q2 is turned on. The upper transistor Q1 is turned off, and the output voltage is approximately equal to V-; when the input signal jumps to low, Q2 turns off and Q1 is turned on, and the output voltage jumps to V+, and the rise time can meet the index of less than 10nS. In this circuit, the regulated voltage values of the Zener diodes D1 and D2 must be precisely matched with the V+ and V- values to drive the downstream transistors Q1 and Q2 to work in harmony. For example, when the signal source is 0 to ±5V, the V+ and V- values are respectively It is 7.7V and -7.7V, and the regulated voltage values of D1 and D2 are also different; otherwise, once the match is improper, the time for Q1 and Q2 to be turned on or turned off at the same time is too long, and the circuit characteristics will deteriorate sharply. Therefore, the pulse amplitude of such a circuit is difficult to achieve programmable adjustment. If you want to realize the program control of the pulse amplitude, one way of thinking is to use multiple sets of Zener diodes to match multiple sets of V+ and V- values, but this will inevitably lead to gear switching. links, resulting in complex circuits and poor reliability. If you want to achieve continuous adjustment of V+ and V-values, you need to subdivide more zener diode gears, and V+ and V-values in some sections will be different from each other. Improper matching of Zener diodes results in degraded pulse edge quality.

Contents of the invention

The purpose of this utility model is to propose a fast edge pulse generating circuit with programmable amplitude without sub-block switching link. In order to overcome the shortcomings of the above circuit, the circuit uses AC coupling instead of DC coupling to solve the sub-blocking caused by voltage matching of Zener diodes. question.

In order to achieve the above purpose, the technical solution of the present utility model is: a fast edge pulse generating circuit with programmable amplitude without step-by-step switching link, including a triode pulse driving circuit, and the control input end of the triode pulse driving circuit is connected with a trigger pulse Input signal; the triode pulse drive circuit includes two triodes, the two triodes are respectively a PNP junction and an NPN junction, the collectors of the two triodes are connected as pulse output terminals, and the bases of the two triodes are the control input terminals, A DC blocking coupling capacitor is respectively connected between the two control input terminals and the trigger pulse input signal, and a DC power supply is alternately connected between the base and the emitter of the two triodes through a switch, and the The DC power supply is used to set the pulse output terminal in the reset state.

The scheme is further as follows: a voltage regulator tube is respectively connected between the bases of the two triodes and the DC blocking coupling capacitor, and the DC power supply is applied between the base and the emitter of the triodes through the voltage regulator of the voltage regulator tube. between.

The scheme is further as follows: the voltage of the direct current power supply is 5 volts, and the regulated voltage of the voltage regulator tube is 2.7 volts.

The solution is further as follows: the switch is a program-controlled switch, an electronic switch controlled by a microprocessor.

The solution is further: the switch is a program-controlled switch, which is an electronic switch controlled by a microprocessor. The output of the electronic switch is connected in series with a resistor. Between the direct coupling capacitor and the voltage regulator tube, when the electronic switch disconnects the DC power supply, the resistor is connected in parallel between the DC blocking coupling capacitor, the voltage regulator tube and the emitter.

The utility model reduces the rising and falling time of the pulse by adding the coupling capacitor and the additional DC power supply, and can realize the bidirectional output pulse according to the input signal; the circuit uses AC coupling instead of DC coupling to solve the voltage matching of the Zener diode The partitioning problem brought about. The circuit can be adjusted and controlled through the program, and the circuit is simple and practical. The utility model provides a fast edge pulse generation circuit with a rise or fall time less than 10 nS, a current drive capability of no less than 0.5 A, and a programmable pulse amplitude, which can meet the test requirements of various small and medium power components.

Below in conjunction with accompanying drawing and embodiment the utility model is described in detail.

Description of drawings

Figure 1 is a schematic diagram of the time parameter test of bipolar transistors for parameter measurement and testing of electronic components;

Fig. 2 is a traditional class D amplifier circuit with a DC coupling structure;

Fig. 3 is a schematic diagram of the utility model logic circuit;

Fig. 4 is a schematic diagram of the positive pulse output circuit of the present invention;

Fig. 5 is a schematic diagram of the negative pulse output circuit of the present invention.

Detailed ways

A fast edge pulse generation circuit with programmable amplitude without step-by-step switching links, as shown in Figure 3, includes a triode pulse drive circuit, the control input of the triode pulse drive circuit is connected to a trigger pulse input signal F; the triode The pulse drive circuit includes two triodes, the two triodes are Q1 of the PNP junction and Q2 of the NPN junction, the collectors c of the two triodes are connected as the pulse output terminal T, and the bases b of the two triodes are the control input terminals , connecting a DC blocking coupling capacitor C1 and C2 between the two control input terminals and the trigger pulse input signal respectively, and alternately passing switches K1 and K2 between the base and the emitter of the two triodes respectively A DC power supply CE1 and CE2 are connected, and the DC power supply is used to set the pulse output terminal to be in a reset state, that is, the two triodes are in a critical conduction state.

In the embodiment: a voltage regulator tube D1 and D2 are connected between the bases of the two triodes and the DC blocking coupling capacitor respectively, and the DC power supply is applied to the base of the triode and the DC blocking capacitor through the voltage regulator of the voltage regulator tube. between the emitters.

In the embodiment: the voltage of the direct current power supply is 5 volts, and the regulated voltage of the voltage regulator tube is 2.7 volts.

In the embodiment: the switch is a program-controlled switch, which is an electronic switch controlled by a microprocessor, the control terminal of the electronic switch is connected to the control output pin of the microprocessor, and the controlled terminals of the electronic switch are respectively connected with resistors R1 and R2, As shown in Figure 3, when the electronic switch connects the DC power supply, the DC power supply CE1 or CE2 is connected in series with a resistor R1 or R2 between the DC blocking coupling capacitor C1 or C2 and the voltage regulator tube D1 or D2. When the DC power supply is disconnected, the electronic switch simultaneously connects the resistor R1 or R2 in parallel between the connection point of the DC blocking coupling capacitor C1 or C2 and the voltage regulator tube D1 or D2 and the emitter of Q1 or between the emitter of Q2 The purpose of the resistor connected above is to make the two triodes in a critical conduction state.

Description of working principle:

As shown in Figure 4, in the positive pulse output circuit from V- to V+, a negative pulse of the same pulse width needs to be applied to the input of the circuit, and this pulse can be generated by a CMOS digital circuit. Before the pulse arrives, first set the input to a high level state, and set the two program-controlled DC power supplies to V+ and V- respectively. At this time, the upper triode Q1 is cut off due to the very small VBE voltage due to the existence of R1, and the lower triode Q2 is turned on because the floating DC power supply CE2 provides the Vbe conduction voltage of Q2 through R2. The AC coupling capacitor plays the role of isolating DC. The voltage that C1 bears is the difference between V+ and the input high-level voltage, and the voltage that C2 bears is the difference between the input high-level voltage and V- plus the voltage of CE2. At the same time, resistors R1 and R2 also provide the charging and discharging paths of C1 and C2. After the circuit is powered on and stabilized, the circuit enters the initial steady state, and the circuit output is low level V- at this time. Appropriately selecting the resistance values of R1 and R2 can obtain a shorter charging time and at the same time meet the requirements of voltage changes on capacitors C1 and C2 within the pulse width.

When the input negative pulse edge comes, because the voltage at both ends of C1 and C2 cannot change abruptly, the bases of the upper transistor Q1 and the lower transistor Q2 are forced to be driven by the negative pulse at the same time, so that the Vbe voltage of Q1 increases and turns on, and the Vbe voltage of Q2 Decrease and cut off, the circuit outputs a positive fast pulse edge, the amplitude is from V- to V+, and the circuit output enters a high-level state. However, C1 and C2 will slowly charge and discharge in this state, so this state is unstable, and the circuit cannot be kept in the output high state, and needs to be reset. The pulse width of this circuit can be maintained above 10uS, which can fully meet the test requirements of time parameters.

When the pulse ends, the circuit can be reset, and the input returns from low level to high level. C1 and C2 play the role of AC coupling again, forcing the bases of the upper transistor Q1 and the lower transistor Q2 to be driven by positive pulses at the same time, Q1 cuts off and Q2 When it is turned on, the circuit output produces a negative fast pulse edge at this time, and the amplitude is from V+ to V-, and the circuit returns to a stable initial state. In the process of completing a complete programmable amplitude pulse, the circuit generates a positive fast pulse edge and a negative fast pulse edge, and both of these two fast pulse edges can be used for the test time parameter.

Conversely, as shown in Figure 5, the circuit of the present invention can also form a negative pulse output circuit form, cut off the floating DC power supply CE2, only need to connect the floating DC power supply CE1 between V+ and R1, and input a positive pulse from the input terminal. Yes, the working principle is the same as the positive pulse output circuit. In addition, V+ and V- each add a group of floating DC power CE1 and CE2, and use a program-controlled switch to switch appropriately, then the arbitrary selection of positive and negative pulse outputs can be realized.

The utility model is applied to a switch parameter testing system of discrete devices, and obtains good application effects.

Claims (4)

1. nothing divides gear to switch a quick edge pulse generating circuit for the program-controlled amplitude of link, and comprise triode pulse driving circuit, the control input end of described transistor drive circuit connects a trigger impulse input signal; It is characterized in that, described transistor drive circuit comprises two triodes, two triodes are positive-negative-positive and NPN knot respectively, the collector electrode docking of two triodes is as pulse output end, the base stage of two triodes is described control input ends, one is accessed respectively every straight coupling capacitance between described two control input ends and trigger impulse input signal, between the base stage and emitter of described two triodes, alternately access a DC power supply respectively by switch, described DC power supply is used for arranging pulse output end and is in reset mode.

2. pulse generating circuit according to claim 1, it is characterized in that, the base stage of described two triodes and also access a voltage-stabiliser tube respectively between straight coupling capacitance, described DC power supply is applied between the base stage of triode and emitter by the voltage of voltage regulation of voltage-stabiliser tube.

3. pulse generating circuit according to claim 1 and 2, is characterized in that, described switch is grammed switch, is by the electronic switch of a Microprocessor S3C44B0X.

4. pulse generating circuit according to claim 2, it is characterized in that, described switch is grammed switch, by the electronic switch of a Microprocessor S3C44B0X, the output of electronic switch is serially connected with a resistance, and when DC power supply connected by electronic switch, DC power supply is connected between straight coupling capacitance and voltage-stabiliser tube by described resistance, when electronic switch disconnects DC power supply, described resistance is attempted by every straight coupling capacitance, between voltage-stabiliser tube and emitter.