PIN Diodes

PIN diodes are three-layer semiconductor diodes consisting of an intrinsic layer separating heavily doped P and N layers. The charge stored in the intrinsic layer in conjunction with other diode parameters determines the resistance of the diode at RF and microwave frequencies. This resistance typically ranges from kilohms to less than 1 ohm for a given diode. A PIN diode is typically used as a switch or attenuator element.

PIN diodes have an intrinsic semiconductor sandwiched between p-type and n-type semiconductor layers. A PIN diode is a semiconductor device that operates as a variable resistor at radio and microwave frequencies and that has the resistance value determined only by forward biased direct current. In switch and attenuator applications, PIN diodes control the radio frequency (RF) signal level without introducing distortion that might change the shape of the radio frequency signal. An important feature of PIN diodes is its ability to control large radio frequency signals while using much smaller levels of direct current excitation. A PIN photodiode is also another name for a positive-intrinsic-negative (PIN) diode. PIN photodiodes are semiconductor light detecting diodes with a particularly fast response time.

A photodiode is a semiconductor diode that produces photo voltage or free carriers, which supports the conduction of photocurrent when photons are absorbed. Photodiodes are used for the detection of optical communication signals and for the conversion of optical power to electrical power. A photodiode can be used as a light detector in phototransistors, which conduct current when exposed to light. A semiconductor diode is a two-element semiconductor device that makes use of rectifying properties in a PN junction in order to convert alternating currents into direct currents by permitting current flow in only one direction. A PN junction (or diode rectifier) is when a section of N-type semiconductor material is joined with a similar section of P-type semiconductor material.

PIN diodes conduct when the anode voltage is higher (more positive) than the cathode voltage. Most PIN diodes used in the microwave industry are made of silicon, but in some applications gallium arsenide (GaAs) is used. A microwave diode (or point contact diode) is a semiconductor diode that operates as a current controlled variable resistor at radio and microwave frequencies. These PIN diodes can amplitude, modulate, or attenuate a radio frequency signal when the forward bias current is varied continuously. Microwave diodes were first constructed as small silicon chips with pointed tungsten wire whiskers pressed against them and used as high frequency semiconductors, mixers, or detector diodes in high frequency receivers.

• Comparison of Bulk and Epitaxial PIN Diodes in Low-Cost Wideband RF Switching - White Paper
  Both electromechanical and semiconductor switches are proven technologies used in the control and routing of RF signals. While the use of mechanical switches can be justified in precision test...
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• AG312: Designing with PIN Diodes
  The PIN diode finds wide usage in RF, UHF and microwave circuits. It is fundamentally a device whose impedance, at these frequencies, is controlled by DC excitation. A unique feature of the PIN diode...
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• Applications of PIN Diodes - App Note
  The most important property of the PIN diode is the fact that it can, under certain circumstances, behave as an almost pure resistance at RF frequencies, with a resistance value that can be varied...
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Part Numbers for PIN Diodes