The traditional method to generate pulses in the range of some nanoseconds with high amplitudes, is the using of the avalanche-effect of transistors. However the problem with this method is the poor possibility for parameterizing.
That was the trigger to look for a different way: under using of modern electronic components, a pulse generator, which is parameterizable, was developed. The parameters can be set by using a Windows- or Linux-PC. The pulse width can be adjusted in the range of 3....80 ns; the pulse amplitude in the range of 18...84 V and the pulse repetition rate in the range of 1 Hz to 50 kHz.
Table of Contents
1 Introduction
2 The Idea
3 Selecting the components
4 Circuit diagram and design details
5 Controlling the parameters
Research Objectives and Key Topics
The primary objective of this work is the development of a parameterizable pulse generator capable of producing short, high-amplitude pulses for physical experiments and LED applications, overcoming the limitations of traditional avalanche-transistor methods.
- Design of a parameterizable pulse generator using Current-Feedback-Amplifiers (CFA).
- Implementation of digital control via Windows or Linux PCs using SPI interfaces.
- Optimization of pulse parameters including amplitude (18–84 V), pulse width (3–80 ns), and repetition rate (1 Hz–50 kHz).
- Selection of specific electronic components (THS3202, LM6172, MRFE6VS25NR1) to meet high slew rate and power requirements.
- Strategic PCB layout considerations to mitigate parasitic effects and ensure circuit stability.
Excerpt from the Book
3 Selecting the components
With respect on the availability and to limit or lower warehousing, the aim was in this case, to use standard electronic components. The choice fell on the CFA-amplifier THS3202 from Texas Instruments, because of its high slew rate about 9 V/ns. Additional, this component can deliver output currents up to 115 mA and voltages up to 13 V. This is helpful to toggle the FET at the output. Details about the THS3202 can be found in [5].
In fact, the THS3202 is designed to work in HF amplifier. The basic idea here was now, to use this component as a comparator. This mode of operation is not recommended from the manufacturer of this component. They do not support this. However, it works - how this application shows.
For the VFA the type LM6172 is used. The slew rate of this device is 3V/ns. This is fast for a VFA. Details about the LM6172 can be found in [6].
For selecting the FET, the Gate-Source-capacity is a very important point. It must be as small as possible. On the other hand, only a transistor which supports a high drain-source voltage, can supply high output amplitude. Both requirements are contradictory, so that a careful selection of the type is necessary. The type MRFE6VS25NR1 (details see [7]) satisfies both contradictory features for the task very well. With the type, output pulses with amplitudes up to 120V (including a safety distance) are realisable.
If instead of an FET a bipolar transistor should be used, [8] can be helpful to get a short switching time.
Chapter Summaries
1 Introduction: This chapter outlines the necessity for high-energy short pulses in particle physics and identifies the limitations of existing avalanche-effect and ECL-based pulse generation methods.
2 The Idea: This section presents the conceptual design of a pulse-shaper utilizing a Current Feedback Amplifier as a comparator to control signal timing and pulse width.
3 Selecting the components: This chapter details the criteria for choosing specific electronic components like the THS3202 and LM6172 to achieve high performance under unconventional operating conditions.
4 Circuit diagram and design details: This section covers the complete technical implementation, including energy storage considerations via capacitors and essential layout guidelines for high-frequency signal integrity.
5 Controlling the parameters: This chapter describes the user interface and hardware communication protocols (SPI, USB) used to adjust pulse repetition, amplitude, and width dynamically.
Keywords
Current-Feedback-Amplifier, CFA, Pulse Generator, Nanosecond Pulses, Comparator, Slew Rate, Particle Physics, Circuit Design, PCB Layout, THS3202, LM6172, SPI Interface, Pulse Shaping, High Amplitude, Electronic Workshop.
Frequently Asked Questions
What is the fundamental purpose of this work?
The work focuses on designing a robust, parameterizable pulse generator that provides high-amplitude pulses for advanced physical experiments and ultra-short light pulse generation.
What are the primary technical fields covered?
The research encompasses electronics engineering, specifically high-frequency signal processing, power electronics, and circuit design optimization.
What is the core objective of the developed device?
The goal is to generate short pulses with amplitudes between 18 V and 84 V, with adjustable widths (3–80 ns) and repetition rates up to 50 kHz, controlled via standard PC interfaces.
Which scientific methodology is applied here?
The author uses a hybrid experimental approach, utilizing standard electronic components in non-traditional configurations (e.g., using a CFA as a comparator) and validating the results through prototype development and circuit analysis.
What does the main body of the text discuss?
It provides an in-depth analysis of the circuit concept, component selection criteria, specific design constraints, and the integration of digital parameter control.
How would you categorize the primary keywords?
The keywords relate to electronic circuit components, signal specifications, and control methodologies involved in high-speed pulse generation.
Why is the PCB layout critical in this design?
Precise layout is essential to minimize parasitic capacitive and inductive components that would otherwise degrade the short-duration, high-energy pulses.
How is the pulse amplitude regulated?
The pulse amplitude is managed via an independent boost converter module ("HV-Generation"), which is controlled through an SPI-bus interface.
Why are standard CFA chips used in non-recommended ways?
Using CFAs as comparators allows for superior signal shaping and higher performance than outmoded methods, despite manufacturers not officially supporting this mode of operation.
What role does the capacitor C2 play in the circuit?
Capacitor C2 acts as the primary energy reservoir for the high-amplitude pulse, as the main power supply cannot provide the necessary current spikes within such short nanosecond intervals.
- Arbeit zitieren
- Dipl.-Ing.(TU) Franz Peter Zantis (Autor:in), 2013, Generating of short pulses with high amplitudes by using of standard Current-Feedback-Amplifier, München, GRIN Verlag, https://www.grin.com/document/265723
