CN104586435A - Pulse bandwidth and amplitude adjustable broadband high-pressure narrow pulse system and pulse generating method - Google Patents

Abstract

The invention belongs to the technical field of high-frequency and high-voltage pulses, and discloses a broadband high-voltage narrow pulse system and a pulse generation method with adjustable pulse width and amplitude. The system includes a control signal adjustment module, a MOSFET drive module, a P-type MOSFET and an N-type MOSFET, and a pulse width The value adjustment module, the control signal adjustment module is connected to the MOSFET drive module, the MOSFET drive module is connected to the P-type MOSFET and the N-type MOSFET, and the pulse amplitude adjustment module is connected to the P-type MOSFET and the N-type MOSFET. The pulse width and amplitude generated by the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude of the present invention are easy to adjust and control, and the pulse frequency is very high, which can be used to improve the corresponding performance of the high-frequency ultrasonic imaging system, and can also meet Transducer testing and imaging applications at different frequencies.

Description

Broadband high-voltage narrow pulse system with adjustable pulse width and amplitude and pulse generation method

technical field

The invention belongs to the technical field of high-frequency and high-voltage pulses, and relates to a high-frequency and high-voltage pulse system and a pulse generation method, in particular to a broadband high-voltage narrow pulse system and a pulse generation method with adjustable pulse width and amplitude.

Background technique

The high-voltage pulse excitation module is a key component in ultrasonic equipment. In the ultrasonic imaging system, the transducer is excited by high-voltage pulses to generate ultrasonic waves, and then the transducer receives tissue reflection echo signals for imaging. The high-voltage pulse transmission module is an important part of the pulse-echo ultrasonic diagnostic equipment, which has a great influence on the imaging and signal-to-noise ratio of the instrument. The current ultrasonic transducer equipment generally works below 20MHz, and the corresponding excitation pulse frequency is easy to achieve. However, in the fields of intravascular ultrasound and ophthalmology, in order to obtain good lateral resolution, the transducer generally works above 20MHz, even up to 60MHz. Correspondingly, a higher frequency pulse signal is required to excite the transducer . In addition, the high-voltage pulse transmission module can not only be used alone as a test module for high-frequency transducers, but also can be integrated in the system as a sub-module of an ultra-high-frequency ultrasonic application instrument.

Contents of the invention

The technical problem to be solved: In the conventional ultrasound imaging system, the bandwidth and amplitude of the excitation signal are not easy to adjust and control, and the pulse frequency is low, which cannot better meet the needs of the ultrasound imaging system.

Technical solution: In order to solve the above problems, the present invention discloses a broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, including a control signal adjustment module, a MOSFET drive module, a P-type MOSFET and an N-type MOSFET, and a pulse amplitude adjustment module. The signal adjustment module is connected to the MOSFET drive module, the MOSFET drive module is connected to the P-type MOSFET and the N-type MOSFET, and the pulse amplitude adjustment module is connected to the P-type MOSFET and the N-type MOSFET.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the control signal adjustment module includes a pulse signal source, a logic level conversion device or a logic level conversion circuit, a pulse width control part, a P-type MOSFET and a N Type MOSFET drive pulse timing adjustment section.

In the broadband high voltage narrow pulse system with adjustable pulse width and amplitude, the pulse signal source is field programmable gate array or microprocessor MCU, general AC signal source, crystal oscillator, DSP, ARM or CPLD input.

In the wide-band high-voltage narrow-pulse system with adjustable pulse width and amplitude, the pulse width control part includes a delay device and a NOT gate and an AND gate; the positive pulse output through logic level conversion is divided into two paths, and one path is connected after passing through the NOT gate. Delay processing, and then connected with another channel to the AND gate, it becomes a control signal with a specific pulse width, and the control signal with a specific pulse width outputs a pulse width; the control signal with a specific pulse width is divided into two channels, which are respectively delayed to match the P-type MOSFET and N-type MOSFET turn-on and turn-off time, connected to the MOSFET driver module.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the delay device is a single delay device DS1100U, multiple DS1100U, or a coaxial cable.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the delay device includes a clock, a counter and a delay network.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the pulse amplitude adjustment module includes a high-voltage power supply and a high-voltage output adjustment part.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the high-voltage power supply is a high-voltage positive power supply EMCO-CA02P and a high-voltage negative power supply EMCO-CA02N, and the digital-to-analog converter is connected to the high-voltage positive power supply EMCO-CA02P and high-voltage negative power supply. The voltage output adjustment port of the power supply EMCO-CA02N can adjust the high voltage output and realize the pulse amplitude adjustment.

In the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude, the high-voltage power supply is a positive power supply EMCO-CA02P, connected to a P-type MOSFET, and the output pulse is a positive pulse; the high-voltage power supply is a negative power supply EMCO-CA02N, connected to an N-type MOSFET, The output pulse is a negative pulse; the high-voltage power supply is a positive power supply EMCO-CA02P and EMCO-CA02N, respectively connected to a P-type MOSFET and an N-type MOSFET, and the output pulse is a bipolar pulse.

The pulse generation method of the broadband high voltage narrow pulse system with adjustable pulse width and amplitude:

The signal at the signal input terminal is connected to the control signal adjustment module, and the control signal adjustment module divides the input signal into two channels, one of which is delayed by a non-gate delay device; the other is connected to an AND gate, and the output terminal of the AND gate generates ns-level narrow pulses , the pulse width is determined by the delay time; the narrow pulse is divided into two signals, the delay matches the opening and closing of the dual-channel MOSFET, and controls the driving of the MOSFET, thereby turning on or closing the dual-channel MOSFET; the output is adjusted by changing the width of the control pulse the pulse width of the pulse;

The pulse output amplitude is achieved by changing the output amplitude of the high-voltage power supply; the working principle of the system is shown in Figure 1.

Through the logic level conversion device or circuit, the control signal (such as LVPECL, LVDS) output by the programmable device (such as field programmable gate array programmable device, microprocessor MCU) to the pulse module control level (such as LVTTL, TTL) is realized ) conversion, or directly use the signal source input signal.

The delay processing part realizes the change of pulse width, and also realizes the change of pulse width and pulse center frequency:

The principle is as follows:

Because the device that generates the pulse works in the pulse switching state, assuming the pulse is ideal, the conduction characteristic can be replaced by a rectangular voltage function, and the principle of adjusting the frequency by changing the pulse width is as follows. , Figure 7c, Figure 7d:

The original waveform is ,

a>1 time domain compression, frequency domain expansion a times; 0<a<1 time domain expansion, frequency band compression;

The decrease of pulse width corresponds to the increase of pulse-3dB cut-off frequency;

Therefore, a higher frequency corresponds to a narrower pulse width; delay the positive pulse with a pulse width of Ta generated by the signal generator, and the delay time is Tb (Tb<Ta), and then compare the delayed signal with the original signal Perform logical AND, so that theoretically a pulse with a pulse width of (Ta-Tb) can be obtained, as shown in Figure 8 of the specification.

because , so the amplitude of the high-voltage pulse changes, corresponding to the cut-off frequency of the pulse will also change.

Signal generator or other signal sources (crystal oscillator, programmable device output) generate square wave pulses;

Shape the waveform of the signal generator through the NOT gate to reduce the rising edge and falling edge time of the signal;

The signal is divided into two paths, one path is delayed by the NOT gate, and the delay is a, and then connected to the AND gate with the other signal, after AND gate processing, theoretically, a positive pulse with a pulse width of a can be obtained;

Using a signal with a pulse width as a switch control signal of the P-channel MOSFET and the N-channel MOSFET;

The control signal controls the MOSFET drive to turn on or off the dual-channel MOSFET;

The programmable device controls the output of the high-voltage power supply, thereby changing the amplitude of the output waveform.

Beneficial effects: the broadband high voltage narrow pulse system with adjustable pulse width and amplitude and its generation method of the present invention have the following advantages:

1. The control signal can be connected from the signal generator, and through the conversion of logic gates and delay devices or circuits, a very narrow pulse width can be obtained from a control signal with a large pulse width and a low frequency (it can be a low frequency clock signal). control signal. Logic gates use NOT gates and AND gates; control signals can also be obtained through logic level conversion, such as using various logic conversion devices to realize LVPECL, LVDS, CMOS and other levels from programmable devices, CPLDs, DSPs, MCUs and other devices. Convert to logic levels such as LVTLL, TTL, etc., and then on the basis of these logic level signals, convert them again through logic gates and delay devices to obtain signals with narrow pulse widths. For example, the programmable device FPGA outputs LVPECL logic signals, and the logic conversion chip SN65LVELT23DGK converts the differential signals into LVTTL levels, thereby realizing the connection and transmission of remote control signals to the pulse module.

2. The control of pulse width is realized by delay devices (such as DS1100U series chips) and AND logic devices. The delay device includes and is not limited to a single delay IC, and several delay devices can be connected in series to achieve a specific delay value. In order to realize the delay value from 5ns to hundreds of ns, it is more accurate and easy to control the width of the pulse signal.

3. Different control pulse widths correspond to different output pulse width values. Changing the control pulse width corresponds to changing the center frequency and cut-off frequency of the output high-voltage pulse.

4. The high-voltage output can be adjusted by the programmable device, and the high-voltage pulse amplitude can be adjusted flexibly and conveniently.

5. Use a MOSFET drive with a peak current greater than 10A (such as a drive circuit composed of an integrated drive device, a discrete bipolar transistor, or a field effect transistor push-pull structure), so that the switching speed of the MOSFET can be increased as much as possible, and the rising and falling edges are very small. pulse.

6. Adjust positive and negative high-voltage power supply connections to flexibly obtain positive, negative, and bipolar high-voltage pulses.

Description of drawings

Figure 1 is a schematic diagram of the pulse generation of the broadband high-voltage narrow pulse system with adjustable pulse width and amplitude;

Figure 2 is a structural diagram of a broadband high voltage narrow pulse system with adjustable pulse width and amplitude.

Fig. 3 and Fig. 4 are single bipolar pulse diagrams of embodiment 1.

Fig. 5 and Fig. 6 are single bipolar pulse diagrams of embodiment 2.

Figure 7 is a schematic diagram of adjusting the frequency by changing the pulse width.

Fig. 8 is a pulse diagram with a pulse width of (Ta-Tb).

Detailed ways

Example 1

Field editable gate array output control signal (logic level is LVPECL), connected to SN65LVELT23DGK to convert LVPECL level to LVTTL level, the signal is divided into two channels, one and the other pass through the inverter SN74LVC1G04, and then connect to the delay device DS1100U- 35+ delay 7ns and then connect with another channel to the input terminal of AND gate SN74AHCT1G08, and the output signal of AND gate is divided into two channels, one channel is connected to P-type MOSFET drive device EL7158 after DS1100U delay, and the other channel is connected to DS1100U delay and then connected to N Type MOSFET drive device EL7158, two pieces of EL7158 respectively control the P-type MOSFET and N-type MOSFET to turn on and off, the high-voltage power supply EMCO-CA02P output terminal (pin 1) is connected to the P-type MOSFET source output control terminal (pin 2) to the digital-to-analog converter The output, the input terminal of the digital-to-analog converter is connected to the field programmable gate array, the output of the pulse is controlled by the field programmable gate array, and the source of the N-type MOSFET is grounded. A single positive pulse is shown in Figure 3 and Figure 4.

Example 2

The pulse signal output by the AC signal source Agilent 81150A is used as the input signal, the pulse frequency is 1KHz, the amplitude is 4V, the pulse rise time is 10ns, the fall time is 10ns, and the pulse width is 100ns. The signal is divided into two channels, one channel is inverted by the NOT gate SN74LVC1G04, and then delayed by the delay device DS1100U, and then connected to the input terminal of the AND gate SN74AHCT1G08 with the other input signal, and the output signal of the AND gate is divided into two channels, one channel is delayed by the DS1100U Control the P-type MOSFET to drive the EL7158, so that another DS1100U controls the N-type MOSFET to drive the EL7158 after a delay, and the two EL7158 control the P-type MOSFET and the N-type MOSFET to turn on and off, and the output terminal (pin 1) of the high-voltage power supply EMCO-CA02P is connected to the P-type MOSFET source, the output control terminal (pin 2) is connected to the output terminal of the digital-to-analog converter, the output terminal (pin 1) of the high-voltage power supply EMCO-CA02N is connected to the N-type MOSFET source, and the output control terminal (pin 2) is connected to the digital-to-analog converter output The input terminal of the digital-to-analog converter is connected to the field programmable gate array, and the output of the pulse is controlled by the field programmable gate array. A single bipolar pulse is shown in Figures 5 and 6.

Claims (10)

1. the broadband high voltage narrow pulse system that pulsewidth amplitude is adjustable, it is characterized in that: comprise control signal adjusting module, MOSFET driver module, P type MOSFET and N-type MOSFET, pulse amplitude adjusting module, control signal adjusting module connects MOSFET driver module, MOSFET driver module meets P type MOSFET and N-type MOSFET, pulse amplitude adjusting module access P type MOSFET and N-type MOSFET.

2. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 1, is characterized in that: described control signal adjusting module comprises pulse signal source, logic level translator part or logic level converting circuit, pulse-width controlled part, P type MOSFET and N-type MOSFET driving pulse sequential adjustment member.

3. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 2, is characterized in that: described pulse signal source is field-programmable gate array, Micro-processor MCV, general AC signal source, crystal oscillator, DSP, ARM or CPLD input.

4. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 2, is characterized in that: pulse-width controlled part comprises time delay device and not gate and door; The positive pulse exported through logic level transition divides two-way, and a road connects delay process behind the door through non-, then accesses and door with an other road, becomes the control signal of specific pulsewidth, and specific pulse-width control signal exports pulse; The control signal of specific pulsewidth divides two-way, and respectively through time delay, coupling P type MOSFET and N-type MOSFET opens the shut-in time, access MOSFET driver module.

5. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 4, is characterized in that: described time delay device is single time delay device DS1100U, multiple DS1100U or coaxial line.

6. the broadband high voltage narrow pulse system that pulsewidth amplitude according to claim 4 is adjustable, is characterized in that: described time delay device comprises clock, enumerator and time delay network.

7. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 1, is characterized in that: pulse amplitude adjusting module comprises high voltage power supply and High voltage output adjustment portion.

8. the broadband high voltage narrow pulse system adjustable according to the pulsewidth amplitude described in claim 7, it is characterized in that: described high voltage power supply is high pressure positive supply EMCO-CA02P and high pressure negative supply EMCO-CA02N, digital to analog converter connects the voltage Drazin inverse port of high pressure positive supply EMCO-CA02P and high pressure negative supply EMCO-CA02N, thus adjustment High voltage output, the amplitude realizing pulse regulates.

9. the broadband high voltage narrow pulse system that pulsewidth amplitude according to claim 8 is adjustable, is characterized in that: high voltage power supply is positive supply EMCO-CA02P, meets P type MOSFET, output pulse is positive pulse; High voltage power supply is negative supply EMCO-CA02N, meets N-type MOSFET, and output pulse is negative pulse; High voltage power supply is positive supply EMCO-CA02P and EMCO-CA02N, meets P type MOSFET and N-type MOSFET respectively, exports pulsed bipolar pulse.

10. the production method of the broadband high voltage narrow pulse system pulses that pulsewidth amplitude according to claim 1 is adjustable, is characterized in that described method comprises the following steps:

The signal incoming control signal adjusting module of signal input part, input signal is divided two-way by control signal adjusting module, and a road connects time delay device delay process through not gate; Other road access and a door, produce ns level burst pulse with gate output terminal, pulse width is determined by delay time; This burst pulse is divided into two paths of signals, and delay match double channel MOSFET opens closedown, and control MOSFET drives, thus opens or close double channel MOSFET; The pulsewidth of regulation output pulse is carried out by the width changing control impuls; Pulse output amplitude realizes by changing high voltage power supply output amplitude; System Working Principle is as Fig. 1.