The PN Junction
- 190 Downloads
The use of PN and PIN diodes to switch microwaves is a technology that is over 20 years old. [1, 2] Within that period, many engineers involved in microwave switching have observed that a small dc forward bias current of 100 m/A is sufficient to turn on a PIN diode such that it is essentially a short circuit to microwave signals with current amplitudes of tens of amperes, and that a -100 V dc reverse bias is sufficient to hold the diode in a nonconducting capacitance state even though the peak RF voltage impressed upon it may be as large as 1000 V. This operation is shown diagram-matically in Figure I-1. It would be an understatement to say that such a situation is useful as well as remarkable. But the reasons underlying it often are given too little, even inaccurate, thought. Misleadingly, this important behavior is often explained by an inertial argument — “The diode conduction mechanism cannot respond rapidly enough to follow the RF waveform; hence, its impedance state is established by the dc bias.”
KeywordsMinority Carrier Forward Bias Majority Carrier Junction Potential Depletion Zone
Unable to display preview. Download preview PDF.
- Armstead, M.A.; Spencer, E.G.; and Hatcher, R.D.: “Microwave Semiconductor Switch,” Proceedings of the IRE, Vol. 44, p. 1875, December 1956.Google Scholar
- Phillips, Alvin, B.: Transistor Engineering (Chapters 2–6), McGraw-Hill, Inc., New York, 1962.Google Scholar
- Watson, H.A., (ed.): Microwave Semiconductor Devices and Their Circuit Applications (Chapters 2–7), McGraw-Hill, Inc., New York, 1969.Google Scholar