Schottky Diode Detector
A small-signal Schottky diode rectifies RF power in its square-law region, producing a video (baseband) voltage proportional to the input power. Its usefulness as a detector is set by the current and voltage responsivity, the video (junction) resistance that sets the Johnson noise, and the resulting noise-equivalent power (NEP) and tangential signal sensitivity (TSS). This tool computes all of these from the diode's ideality factor, saturation current, series resistance and bias.
Equations & Parameters ▸
\(V_T=\dfrac{kT}{q},\qquad R_v=\dfrac{nV_T}{I_s+I_b}\) (video resistance)
current resp. \(\beta_i=\dfrac{1}{2nV_T}\cdot\dfrac{R_v}{R_v+R_s}\) (A/W), voltage resp. \(\beta_v=\beta_i R_v\) (V/W)
\(NEP=\dfrac{\sqrt{4kTR_v}}{\beta_v},\quad MDS=NEP\sqrt{B},\quad TSS\approx 2.5\,MDS\)
current resp. \(\beta_i=\dfrac{1}{2nV_T}\cdot\dfrac{R_v}{R_v+R_s}\) (A/W), voltage resp. \(\beta_v=\beta_i R_v\) (V/W)
\(NEP=\dfrac{\sqrt{4kTR_v}}{\beta_v},\quad MDS=NEP\sqrt{B},\quad TSS\approx 2.5\,MDS\)
| n | Diode ideality factor (~1.05–1.2). |
| Is | Saturation current (µA); sets zero-bias video resistance. |
| Rs | Diode series resistance (Ω). |
| Ib | DC bias current (µA); 0 for a zero-bias detector. |
| B, T | Video bandwidth (MHz) and temperature (K). |
Reference: D. M. Pozar, Microwave Engineering, 4th ed., §10.3. TSS uses the conventional ≈2.5× (4 dB) tangential factor.
Inputs
~1.1
µA
Sat. currentΩ
Series RµA
0 = zero-biasMHz
VideoK
PhysicalResults
Responsivity
Video resistance Rv—
Current resp. βi—
Voltage resp. βv—
Sensitivity
Noise voltage—
NEP—
MDS in B—
TSS—