PIN diode bias dependence – Typical dynamic resistance values What are representative resistance values of a PIN diode under strong forward bias and under reverse bias, respectively?

Introduction:
PIN diodes are current-controlled RF resistors. Their I-region stores charge under forward bias, yielding low RF resistance, while reverse bias depletes charge, yielding high RF resistance. Recognizing typical orders of magnitude helps in switch and attenuator design.

Given Data / Assumptions:

• Small-signal RF resistance under bias at the frequency of interest.
• “Strong forward bias” implies sufficient current to fully charge the I-region.
• Reverse bias large enough to maintain depletion.

Concept / Approach:

Under forward bias, the stored charge turns the device into a low-resistance element (often a few ohms), enabling low-loss RF conduction. Under reverse bias, carriers are swept out, making the device a high-resistance element (typically kilo-ohms or more), providing isolation. Exact values depend on geometry and current but the order-of-magnitude pair is stable across devices used for switching and attenuation.

Step-by-Step Solution:

Verification / Alternative check:

Datasheets for microwave PIN diodes specify R_on of a few ohms at tens of milliamps and R_off of kilo-ohms at modest reverse biases, confirming the ranges.

Why Other Options Are Wrong:

Options with nearly equal low resistances ignore depletion; very high forward resistance contradicts operation; 0.1 Ω is unusually low except for power devices, and 100 Ω off-state is too small for isolation.

Common Pitfalls:

Assuming DC resistance equals RF resistance; neglecting frequency-dependent behavior due to stored charge lifetime.

Final Answer:

a few ohms and a kilo ohms.