The Pin Diode Tutorial

Consider using PIN diodes in your RF or microwave circuit design.

A standard diode semiconductor uses a basic PN junction made from two silicon materials pressed together to cause electricity to flow in one direction but not in the other. A PIN diode has an intrinsic layer called an I-region placed between the two elements of the PN junction, thus the name PIN diode. At RF (radio frequency) and microwave frequencies, it works like a variable resistor. To use PIN diodes in electronic circuits, you need to use complex formulas to figure out the characteristics of the diode you need for your particular application, and know how to design electronic circuits.

Instructions

1. Use PIN diodes to replace conventional components in RF and microwave frequency equipment to switch or filter radio signals or to attenuate their power level.

2. Use forward bias on a PIN diode for attenuating circuits. Forward bias means applying a negative control voltage to the cathode. See the reference at www.microsemi.com for exact formulas for your application. The amount of attenuation will depend on the bias current.

3. Use reverse bias by applying a positive voltage to the cathode of a PIN diode for tuning or switching circuits. See the reference at www.microsemi.com for examples of equivalent circuits that you can use PIN diodes to substitute. You must coordinate the type of PIN diode - determined by its overall dimensions and materials - with the design of your circuit and its application.

References

• Wisc-Online: Silicon Diode Basics
• Bill Doherty: PIN Diode Fundamentals