PIN Diode Switch Circuit for Short Time High Current Pulse Signal By
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PIN Diode Switch Circuit for Short Time High Current Pulse Signal by Rogelio Palomera-Arias B.S. Electrical Engineering University of Puerto Rico Mayagiez Campus, 1996 Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering at the Massachusetts Institute of Technology June, 1998 © 1998 Rogelio Palomera-Arias. All rights reserved. The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part. Signature of Author: 1--. -- Department of Electial Engineering and Computer Science May 22, 1998 Certified by: / -Dr. Chathan M. Cooke ncipal Research Engineer / ~-hesjs Superxwisor Accepted by: Professor Arthur C. Smith Chair, Department Committee on Graduate Students L'~n ~'" "If your problems have solution, no need to worry. If your problems have no solution, why worry?" - Anonymous PIN Diode Switch Circuit for Short Time High Current Pulse Signal by Rogelio Palomera-Arias Submitted to the Department of Electrical Engineering and Computer Science on May 22, 1998 in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering ABSTRACT The protection of devices from transients is an important general problem and is investigated here in regard to a circuit with a sensor and transient pulses. The specific problem uses a sensor connected in series with a fast pulse source, of about hundred nano seconds duration and five hundred volts size. The method of protection employed is based on using both series isolation and a shunt parallel to the sensor. The goal was to keep the sensor isolated during the time of the fast power pulse and then to have the sensor active at all other times. PIN diodes are semiconductor devices commonly used to control RF and microwave signals. Their remarkable and useful aspect arises from their ability to behave as variable resistors in the high frequencies domain and their high power handling capacity using relatively low levels of excitation. PIN diodes are used in this project as solid state switches in order to provide an alternate path for the current and isolate the sensitive sensor throughout the high voltage pulse. A prototype of the protection circuit was built using PIN diodes in a modified series-shunt configuration in order to provide a high isolation during the pulse application while allowing the sensor to be active and perform its required measurements when the pulse is not present. Thesis Supervisor: Dr. Chathan. M. Cooke Title: Principal Research Engineer Acknowledgments A mifamilia, gracias por su confianza y apoyo infinitos. Thanks to Dr. Chathan Cooke for his kind help, and the opportunity to do this thesis under his supervision. To The Office of the Dean of Graduate Education, thanks for their help, support, friendship, resources and free food. Specially to Dean Colbert and Dean Tyler for their help and support in the non-academics matters needed to survive at MIT. Table of Content Chapter 1 Introduction ....... 1.1 System Overview ....... 1.2 System Modules Description ... ... .... ... 1.3 Project Overview ....... ............. .. .. ............. Chapter 2 PIN Diode Theory ........................................... 11 2.1 General Description ............................................. 11 2.2 Forward Bias Operation .......................................... 11 2.2.1 Forward Bias Resistance with Sinusoidal Signals ....................... 12 2.2.2 Forward Bias Equivalent Circuit .................................. 14 2.3 PIN Diode in Reverse Bias ......................................... 14 2.3.1 Operation Description ......................................... 14 2.3.2 Reverse Bias Equivalent Circuits and Dielectric Relaxation Frequency ......... 15 2.4 Switching Speed Characteristic ..................................... 17 2.4.1 turn-off time: Forward to Reverse Bias .............................. 17 2.4.2 Turn-on time: Reverse to Forward Bias .............................. 18 2.5 PIN Diode Lim itations ............................................ 19 Chapter 3 Diode Characterization ......................................... 21 3.1 Basic Test Circuit ............................................... 21 3.2 Forward Bias I-V Curves .......................................... 22 3.3 D iode Resistance ............................................... 23 3.4 Switching Speed: On and Off. ...................................... 25 3.4.1 Experimental Turn-off Time ..................................... 25 3.4.2 Experimental Turn-on Time ..................................... 27 3.5 Switching Pulse Impedance ........................................ 29 Chapter 4 The Two Diode Circuit ........................................ 32 4.1 General Description ............................................. 32 4.2 Two Diode Circuit Operation ....................................... 33 4.2.1 Steady State Analysis .......................................... 33 4.2.2 Transient Analysis ............................................ 36 4.3 Circuit Experimental Behavior . ........... ............. 4.3.1 Circuit Response in Fixed State ......... ............. ............. I 4.3.2 Circuit Response vs Bias Point IF ....... 4.3.3 Circuit State Transition Response ....... .............. 4.4 Pulse Impedance during Circuit State Transition Chapter 5 Conclusions .......................... 42 5.1 General Problem .......................... 42 5.2 PIN D iodes ............................ 42 5.3 Two Diode Protection Circuit ................. 43 Appendix A: Microsemi Diodes Experimental Characterization Appendix B: Microsemi Diodes Data Sheets ............ B .1 U M 2104 ............................... B .2 U M4002 ............................. B .3 U M 6204 ............................... Appendix C: Two Diode Circuit Matlab Scripts for Steady State Computations C. 1 Shunt Diode Operation Point . ...... ..... ...... .... C.2 Series Diode Operation Point . .. ......... ........ C.3 Transfer Function Computation ..................... Bibliography ...................... List of Figures Figure 1.1 Complete System Block Diagram ................................ 9 Figure 2.1 PIN Diode Structure .......................................... 11 Figure 2.2 PIN diode sample (a) I-V characteristic and (b) Forward Bias Series Resistance 13 Figure 2.3 Forward Bias Equivalent Circuits (a) low frequency; (b) high frequency ...... 14 Figure 2.4 Reverse Bias PIN Diode Model .................................. 15 Figure 2.5 Pin Diode (a) Resistance and (b) Capacitance vs. Reverse Voltage Example .... 15 Figure 2.6 Reverse Bias Equivalent Circuits: (a) Low frequency; (b) High frequency ..... 16 Figure 2.7 turn-off PIN diode current. ..................................... 17 Figure 2.8 Typical PIN diode turn-on transient ............................... 18 Figure 3.1 Basic Diode Circuit used for Characterization ........................ 21 Figure 3.2 Experimental I-V Curves for PIN Diodes UM2104, UM4002 & UM6204 ..... 22 Figure 3.3 Data sheet vs. Experimental I-V Curves ............................ 23 Figure 3.4 Low frequency and High frequency resistance vs. Bias current. ............ 24 Figure 3.5 High Frequency Resistance Comparison ............................ 24 Figure 3.6 Recombination Time Effect on Turn-off Time ........................ 26 Figure 3.7 Effect of Peak Reverse Current on Turn-off Time for Diode UM4002 ........ 26 Figure 3.8 Effect of Forward Bias on Turn-off Time for Diode UM4002 ............. 26 Figure 3.9 Reverse Voltage Effect on Turn-on Time for Diode UM4002 .............. 28 Figure 3.10 Forward Bias Effect on Turn-on Time for Diode UM4002 ............... 28 Figure 3.11 Effect of Transit Time on Turn-on Time ........................... 28 Figure 3.12 PIN Diode UM4002 Current and Voltage Waveforms for Positive Pulse ..... 30 Figure 3.13 PIN Diode UM4002 Current and Voltage Waveforms for Negative Pulse ..... 31 Figure 4.1 Ccmplete Test System ........................................ 32 Figure 4.2 Two Diode Simplified System Circuit ............................. 33 Figure 4.3 Small Signal Conduction State Equivalent Circuit ...................... 34 Figure 4.4 Isolation Mode Small Signal Equivalent Circuit ....................... 35 Figure 4.5 Circuit Gain vs. Bias Current ................................... 38 Figure 4.6 Circuit Switching Time Response (D1 & D2 are UM4002) ............... 38 Figure 4.7 Circuit Conduction to Isolation State Pulse Transmission with UM4002 diodes . 40 Figure 4.8 Circuit Isolation to Conduction State Pulse Transmission with UM4002 diodes .. 40 Figure 4.9 Circuit Isolation variation with Time during transition to the Isolation State ..... 41 List of Tables Table 3.1 PIN Diode's Manufacturer Electrical Characteristics ................... 22 Table 3.2 PIN Diodes Experimental Carrier Lifetime (t) Values and Turn-off Times ...... 27 Table 3.3 turn-on Times for Three Diodes with Different Carrier Lifetimes ............ 29 Table 3.4 UM4002 PIN Diode Pulse Impedances ............................. 29 Table 4.1 Two Diode Circuit Model Transfer Functions ......................... 36 Table 4.2 Two Diode Circuit Steady State Results ............................. 37 Table 4.3 Single Diode and 2 Diode Circuit State Transition Times .............. 39 Chapter 1 Introduction 1.1 System Overview An electrical measurement system with a series connected sensor is to be protected.