of University Pennsylvania
Department of Electrical and Systems Engineering
ABSTRACT:
PIN diodes are used in solid state transmit-receive (TR) switches that allow either the transmitter or the receiver to communicate with the antenna while protecting the device not in use. In some devices, e.g. radar and radios, PIN diodes are required to handle powers on the order of 1 kW at radio frequencies (RF). The problem that a designer of solid state switches faces is testing the diodes and the switch circuit with stresses of high power. Test equipment that provides power of 1 kW is expensive to purchase or rent. One method to limit the need of a high power RF transmitter is to create resonant circuits that can provide either the high voltage or high current that would be seen from a high power source. High voltage can be achieved through series resonating circuits while high current can be produced with parallel resonating circuits. The circuits will be designed to resonate at several frequencies ranging between 10 MHz and 300 MHz. The PIN diode can be stressed with these tuned circuits and a designer would have the ability to find faults in the solid state TR switch being designed without the costs and dangers associated with a high power transmitter. The resonating circuits will provide solid state TR switch designers a low power and low cost method of testing PIN diodes. Authors: Philip Chan ESE 05 Michael Chakardjian ESE 05 Thomas Leonard ESE 05 Advisor: Philip Farnum Demo Times: Thursday April 21st 10:00AM, 10:30AM, 11:00AM, 1:00PM Group number 17
PIN Diode Tester
Design Approach: The PIN diode under test is connected across two terminals from a passive LC circuit. The output of an AC signal is generator fed to the system and amplified by the High Power Amplifier. Then the amplified signal excites the passive Tuned Circuit, generating in one case a high AC voltage (~220 Vrms) or in the other a large AC current. The high voltage mode is used to test the blocking properties of a reverse biased PIN, while large AC currents are used to characterize the PIN in the forward bias. There is a separate tuned circuit for each mode of operation at four operating frequencies in the range from 10 to 300 MHz.
System Block Diagram
Signal Generator DC Voltage Supply
High Powered Amplifier
Tuned Circuit
PIN Diode
PIN Diodes
The PIN diode contains intrinsic material in between p-type and n-type material. The wider the intrinsic region is made, the slower the switching speed of the diode. If the intrinsic region is large enough, then there can be a voltage swing that is opposite of the bias direction but it will not switch because of the slow switching speed. As a result, a low DC bias; low as compared to the am...