Compact subnanosecond pulse source based on step recovery diode

Abstract

The application discloses a kind of small sub-nanosecond pulse sources based on step recovery diode, including drive module, field effect transistor and step recovery diode;Trigger square wave is connected with the gate of field effect transistor by drive module, the drain of field effect transistor is connected with power supply by inductance L1, the source of field effect transistor is grounded, one end of capacitor C1 is connected with the drain of field effect transistor, the other end of capacitor C1 is grounded by inductance L2 and capacitor C2, the cathode of step recovery diode is connected with one end of inductance L3 and capacitor C3, and sub-nanosecond pulse is coupled to load by capacitor C3.The amplitude of sub-nanosecond pulse output by the sub-nanosecond pulse source can break through the limitation of power supply voltage, reach 2-3 times of power supply voltage, and only needs a low-voltage positive power supply.In addition, the pulse source has very low requirements for trigger square wave, and the pulse source has the significant advantages of small size and low power consumption.

Description

Technical Field

[0001] This invention relates to the field of pulse power, specifically to a small sub-nanosecond pulse source based on a step recovery diode. Background Technology

[0002] Subnanosecond pulses have been widely used in ultra-wideband transceivers for various applications, including ground-penetrating radar, indoor positioning technology, and medical imaging systems. In recent decades, portable applications have increasingly demanded miniaturization of pulse sources and have increasingly desired subnanosecond pulses with high pulse amplitude and low ringing to reduce time aliasing of received signals and improve their signal-to-noise ratio.

[0003] Existing subnanosecond pulse generation technologies include methods based on avalanche transistors, tunneling diodes, and step recovery diodes. However, pulse sources based on avalanche transistors typically require a supply voltage of several hundred volts to operate in avalanche mode; pulse sources based on tunneling diodes can typically only generate low-amplitude subnanosecond pulses below 2 volts; and pulse sources based on step recovery diodes typically require both positive and negative power supplies, and the amplitude of the output pulse is limited by the supply voltage and the amplitude of the input pulse. Furthermore, the complex design and high power consumption result in existing pulse sources having a large size, making them difficult to integrate into portable devices. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a small sub-nanosecond pulse source based on a step recovery diode. The amplitude of the sub-nanosecond pulse output by this pulse source can break through the limitation of the power supply voltage, and the pulse source has significant advantages of small size and low power consumption.

[0005] This invention is achieved through the following technical solution:

[0006] A small sub-nanosecond pulse source based on a step recovery diode includes a trigger signal shaping circuit and a sub-nanosecond pulse circuit connected thereto. The sub-nanosecond pulse circuit includes a step recovery diode SRD, a capacitor, and an inductor.

[0007] One end of capacitor C1 contacts the output terminal of the signal shaping circuit, triggering the input terminal of the signal shaping circuit to generate a square wave V. s The other end of capacitor C1 is grounded through inductor L2 and capacitor C2. The anode of step recovery diode SRD is connected to the junction of capacitors C1, C2, and inductor L2. The cathode of step recovery diode SRD is connected to one end of inductor L3 and capacitor C3. The other end of inductor L3 is grounded. The sub-nanosecond pulse is coupled to the load R through capacitor C3. L ;

[0008] Under the control of the trigger signal shaping circuit, energy is stored in inductor L3, and the charge in step recovery diode SRD is depleted, causing it to turn off. Inductor L3 then begins to supply energy to the load R. L Discharge generates a sub-nanosecond pulse with an amplitude higher than the power supply voltage.

[0009] Preferably, the trigger signal shaping circuit includes a driving module, a transistor Q, and an inductor L1;

[0010] One end of the driving module is connected to the trigger square wave V. s The other end of the drive module is connected to the gate of transistor Q, and the drain of transistor Q is connected to the power supply V through inductor L1. CC The source of transistor Q is grounded, and the drain of transistor Q is connected to capacitor C1.

[0011] Preferably, the drive module includes a charging branch and a discharging branch connected in parallel.

[0012] Preferably, the charging branch includes a diode D1 and a resistor R1 connected in series; the discharging branch includes a diode D2 and a resistor R2 connected in series.

[0013] The anode of diode D1 and the cathode of diode D2 are connected and then connected to the trigger square wave V. s The output terminal is connected, and resistors R1 and R2 are connected to the gate of transistor Q.

[0014] Preferably, the transistor Q is an N-channel transistor.

[0015] Preferably, the trigger square wave V s The frequency is 1MHz, the high level is 3.3V, and the low level is 0V.

[0016] Preferably, the power supply V CC The voltage is less than 12V.

[0017] Preferably, the load R L It is 50 ohms.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] The miniature subnanosecond pulse source based on a step recovery diode provided by this invention can be applied to any application requiring a high-voltage subnanosecond pulse source. The trigger signal shaping circuit initially shapes the input trigger signal, generating a negative polarity pulse with high current driving capability. Under the control of the trigger shaping circuit, current flows through inductor L3 in the positive direction of i4, storing a large amount of energy. Immediately afterwards, the charge in the step recovery diode SRD is depleted, and the step recovery diode quickly cuts off. Inductor L3 then begins to supply current to the load R. LDischarge generates a sub-nanosecond pulse with a high voltage amplitude. The amplitude of the sub-nanosecond pulse is determined by the inductance value and the rate of change of the current flowing through it, i.e., the value of inductor L3 and the cutoff time of SRD. This sub-nanosecond pulse source uses a step recovery diode as its core component, and the width of the output pulse can be as narrow as 200ps. The amplitude of the sub-nanosecond pulse output by this pulse source can break through the limitation of the power supply voltage, reaching 2-3 times the power supply voltage, and reaching more than 15V. The output waveform has no obvious ringing and only requires a low-voltage positive power supply (usually less than 12V). In addition, this pulse source has very low requirements for the trigger square wave, especially the amplitude and edge time of the trigger square wave, which are not strictly limited. Thanks to the simple circuit structure, this pulse source has significant advantages in small size and low power consumption. Attached Figure Description

[0020] Figure 1 This is a circuit diagram of the small sub-nanosecond pulse source based on a step recovery diode according to the present invention.

[0021] Figure 2 This is a schematic diagram showing the voltage and current at a key node of the small sub-nanosecond pulse source based on a step recovery diode in this invention.

[0022] in, Figure 2 a is a voltage diagram. Figure 2 b is a schematic diagram of the current. Figure 2 c. Voltage details at a specific time within the same cycle. Figure 2 d. Current details at a specific time within the same cycle.

[0023] Figure 3 This is a sub-nanosecond pulse waveform diagram of the small sub-nanosecond pulse source based on a step recovery diode according to the present invention;

[0024] in, Figure 3 a represents the waveforms of sub-nanosecond pulse sources with different R2 values ​​when L3 = 10nH, where the pulse waveforms of approximately 0ns and 500ns are stretched;

[0025] Figure 3 b. Waveforms of sub-nanosecond pulse sources with different inductance values ​​L3. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.

[0027] Please see Figure 1 The present invention provides a small sub-nanosecond pulse source based on a step recovery diode, comprising a driving module, a field-effect transistor Q, and a step recovery diode SRD.

[0028] One end of the driving module is connected to the trigger square wave V. sThe other end of the drive module is connected to the gate A of the field-effect transistor Q, and the drain B of the field-effect transistor Q is connected to the power supply V through the inductor L1. CC The source of the field-effect transistor Q is grounded.

[0029] One end of capacitor C1 is connected to the drain B of field-effect transistor Q, and the other end of capacitor C1 is grounded through inductor L2 and capacitor C2. The anode of step recovery diode SRD is connected to the junction of capacitors C1, C2, and inductor L2. The cathode of step recovery diode SRD is connected to one end of inductor L3 and capacitor C3, and the other end of inductor L3 is grounded. The other end of capacitor C3 is connected to the load R. L The sub-nanosecond pulse is coupled to the load R through capacitor C3. L .

[0030] The drive module includes a charging branch and a discharging branch connected in parallel.

[0031] The charging branch includes a diode D1 and a resistor R1 connected in series, with the connection point being the cathode of diode D1; the discharging branch includes a diode D2 and a resistor R2 connected in series, with the connection point being the anode of diode D2.

[0032] After the anode of diode D1 and the cathode of diode D2 are connected, they are connected to the trigger square wave V. s The output terminal is connected, and resistors R1 and R2 are connected to the gate of the field-effect transistor Q.

[0033] In this embodiment, the trigger square wave V s The frequency is 1MHz, the high level is 3.3V, the low level is 0V, and the power supply is V. CC The voltage is 5V, and the load R L It is 50 ohms. It should be noted that the above description of the trigger square wave, power supply, and load illustrates only certain embodiments of the invention and should not be considered as a limitation of the scope.

[0034] The working principle of the small sub-nanosecond pulse source based on a step recovery diode provided by this invention will be described in detail below.

[0035] The pulse source is triggered by a periodic square wave V s Driven by this, it enters a steady state after a period of time (less than 1ms) and can stably generate sub-nanosecond pulses.

[0036] Once the sub-nanosecond pulse source reaches a steady state, the trigger square wave V... s Before the voltage level changes from low to high, a forward current flows through the step recovery diode SRD due to the energy storage effect of inductors L1 and L2. At this time, a large amount of charge is stored in the PN junction of the step recovery diode SRD.

[0037] When the square wave V is triggered s When the voltage level changes from low to high, the gate of the field-effect transistor Q charges the resistor R1 through the diode D1, thus turning on the field-effect transistor Q. Therefore, the drain voltage of the field-effect transistor Q gradually decreases, and the inductor L1 begins to discharge to ground through the field-effect transistor Q. The inductor L2 also discharges to ground through the capacitor C1 and the field-effect transistor Q.

[0038] At this time, the charge stored in the step recovery diode SRD also begins to be released, so the current flowing through the step recovery diode SRD is reversed. The charge in the step recovery diode SRD discharges through the circuit formed by inductor L3, step recovery diode SRD, capacitor C1, and field-effect transistor Q. Since the impedance of the above circuit is very small, the current flowing through the circuit is very large, that is, the current flowing through inductor L3 is very large.

[0039] According to the working principle of the step recovery diode SRD, during the release of the charge stored in the PN junction of the step recovery diode SRD (i.e., the current flowing through the SRD is reversed), the step recovery diode SRD does not immediately turn off. Instead, it suddenly turns off when the stored charge is about to be released. The time from the turn-on to the turn-off of the step recovery diode SRD is called the switching time. The switching time is determined by the manufacturing process of the step recovery diode SRD, the resistance of the circuit, and the parasitic capacitance.

[0040] According to circuit principles, when the step recovery diode SRD is rapidly turned off, the current flowing through inductor L3 cannot change abruptly. Therefore, the energy stored in inductor L3 will be transferred to the load R through capacitor C3. L The pulse is released, forming a sub-nanosecond pulse. The rise time of the pulse is mainly determined by the switching time of the step recovery diode SRD, and is basically consistent with the switching time of the step recovery diode SRD. The amplitude and fall time of the pulse are affected by the load R. L The combined effect of inductor L3.

[0041] After a period of time, inductor L2 discharges through step recovery diode SRD again, causing step recovery diode SRD to conduct in the forward direction, and charge is stored again in the PN junction of step recovery diode SRD.

[0042] When the trigger square wave changes from high to low, the gate of the field-effect transistor Q discharges through capacitor C2 and resistor R2, and the field-effect transistor Q is turned off. Since the current in the inductor cannot change abruptly, the current flowing through the inductor L1 flows back through capacitor C1 to the step recovery diode SRD. The current flowing through the step recovery diode SRD increases, and the PN junction of the step recovery diode SRD stores more charge.

[0043] Then, when the trigger pulse changes from low to high, the circuit will repeat the above operating steps.

[0044] The significance of charging and discharging the gate of the field-effect transistor Q through different circuits is as follows:

[0045] Resistor R1 is typically 0 ohms, which allows the field-effect transistor Q to turn on quickly and reduces the heat generated by the field-effect transistor Q. Resistor R2 is typically a few ohms to tens of ohms, which allows the field-effect transistor Q to turn off slowly, thereby reducing the interference of the falling edge of the trigger square wave on the output waveform. However, an excessively large resistor R2 will lead to high power consumption.

[0046] Example 1

[0047] See again Figure 1 For ease of description, the gate of transistor Q is represented as A, the drain as B, the anode of step recovery diode SRD as C, and the cathode as D; the currents through capacitor C1, step recovery diode SRD, capacitor C2, and inductor L3 are represented as i1, i2, i3, and i4, respectively, and the direction indicated by the arrows in the figure is positive.

[0048] Please see Figure 2 Before t = 0 ns, due to the energy stored in inductor L1, the voltage at the drain of the field-effect transistor continues to rise, and the current i2 is positive. Therefore, the step recovery diode SRD is in the conducting state, and the PN junction of the step recovery diode SRD continues to store charge.

[0049] At t = 0 ns, when the rising edge of the trigger square wave Vs appears, the field-effect transistor Q slowly turns on because its drain-source resistance gradually decreases. Therefore, the voltage and current i1 and current i2 at the drain of the field-effect transistor remain stable and then slowly decrease. Figure 2 As shown in d, when the drain-source resistance of the field-effect transistor Q continues to decrease to about 6 ns, the current i2 reverses, and the charge stored in the PN junction of the step recovery diode SRD begins to be released.

[0050] Because the equivalent impedance of the inductor L3, step recovery diode SRD, capacitor C1, and the release circuit of the field-effect transistor Q is very small, the currents i2 and i4 are very large. Because the impedance in the circuit consisting of capacitor C3 and resistor R1 is relatively large, the energy release of the step recovery diode SRD has little effect on the current i3.

[0051] At t = 9.2 ns, the charge stored in the step recovery diode SRD is depleted, and therefore it turns off during the switching time. Inductor L3 begins to supply power to the load R through capacitor C3. L Discharge. Due to the very small switching time of the step recovery diode SRD, the current i3 changes rapidly, resulting in a sharp rising edge and high-amplitude voltage in the output signal Vout, such as... Figure 2 As shown in b.

[0052] The falling edge time of the pulse is affected by the inductor L3.

[0053] At approximately 300 ns, the step recovery diode SRD turns on again due to the energy stored in inductor L2.

[0054] At approximately 500 ns, due to the trigger square wave V s At the falling edge of the voltage drop, the field-effect transistor Q begins to turn off. Diode D2 and resistor R2 help slow down the turn-off process to avoid the energy stored in inductor L1 generating a potentially high voltage at the drain B of the field-effect transistor Q, which could burn out the field-effect transistor Q and cause unwanted ringing in Vout.

[0055] Then, the voltage at the drain B of the field-effect transistor begins to increase, and the step recovery diode SRD continues to store charge until approximately t = 1000 ns, at which point the next rising edge of Vs occurs.

[0056] Please see Figure 3 The beneficial effects of charging and discharging the gate of the field-effect transistor Q through different circuits, such as Figure 3 As shown in Figure a, the waveforms of subnanosecond pulse sources with different inductance L3 values ​​are as follows: Figure 3 As shown in b.

[0057] This invention provides a small sub-nanosecond pulse source based on a step recovery diode, which can be used in all applications requiring high-voltage sub-nanosecond pulse sources, such as ground-penetrating radar, indoor positioning, and medical imaging technologies. The sub-nanosecond pulse source of this invention uses a step recovery diode as its core component, achieving an output pulse width as narrow as 200 ps, ​​a pulse amplitude 2-3 times higher than the power supply voltage, reaching up to 15V or more, and exhibiting no noticeable ringing in the output waveform. This sub-nanosecond pulse source requires only a single low-voltage DC power supply (5V, typically less than 12V), has a stable output waveform, a simple circuit structure, low cost, low power consumption, small size, and strong practicality.

[0058] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A small sub-nanosecond pulse source based on a step recovery diode, characterized in that, It includes a trigger signal shaping circuit and a sub-nanosecond pulse circuit connected thereto, the sub-nanosecond pulse circuit including a step recovery diode. SRD, Capacitors and inductors; capacitance C One end of circuit 1 contacts the output of the signal shaping circuit, while the input of the trigger signal shaping circuit contacts the square wave. V s ,capacitance C The other end of 1 is connected to an inductor. L 2 and capacitor C 2. Grounding, step recovery diode SRD Anode capacitor C 1. Capacitor C 2 and inductance L Connection point 2, step recovery diode SRD Cathode connected inductor L 3 and capacitor C One end of 3, inductor L The other end of 3 is grounded, through a capacitor. C 3. Couple the sub-nanosecond pulse to the load R L ; Under the control of the trigger signal shaping circuit, the inductor L 3. Energy is stored in the step recovery diode (SRD). The charge in the SRD is depleted, causing it to turn off. The inductor... L 3. Start loading R L Discharge generates a sub-nanosecond pulse with an amplitude higher than the power supply voltage. The trigger signal shaping circuit includes a drive module and a transistor. Q and inductor L 1; One end of the driving module is connected to the trigger square wave. V s The other end of the driver module is connected to the transistor. Q gate, transistor Q The drain is through the inductor L 1. Power supply V CC Connection, transistor Q The source is grounded, transistor Q Drain and capacitor C 1 connection; The drive module includes a charging branch and a discharging branch connected in parallel; The charging branch includes diodes connected in series. D 1 and resistance R 1; The discharge branch includes diodes connected in series. D 2 and resistance R 2; The diode D 1 Anode and diode D After the cathode of 2 is connected to the trigger square wave V s Connect the output terminal to the resistor. R 1 and resistance R 2. After connection with transistor Q The gate connection.

2. A small sub-nanosecond pulse source based on a step recovery diode according to claim 1, characterized in that, The transistor Q It is an N-channel transistor.

3. A small sub-nanosecond pulse source based on a step recovery diode according to claim 1, characterized in that, The trigger square wave V s The frequency is 1MHz, the high level is 3.3V, and the low level is 0V.

4. A small sub-nanosecond pulse source based on a step recovery diode according to claim 1, characterized in that, The power supply V CC The voltage is less than 12V.

5. A small sub-nanosecond pulse source based on a step recovery diode according to claim 1, characterized in that, The load R L It is 50 ohms.

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