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Diode_Detectors.php    8512 Bytes    19-06-2024 15:17:46

DIY Diode RF Detectors

Germanium • Schottky

DIY Diode RF Detectors

✈ Single Diode Detector Circuit

DIY Diode RF Detectors

This is the single diode circuit. Use it when the diode is super-expensive or the power is "high". The signal is ac-coupled via C3. A 50 Ω termination is ensured by R3. R1 and D2 perform the rectification. The positive peak value is stored in C1. It is slowly discharged by R4 (tbd). Depending on the use of your diode detector, R4 has to be chosen therfore. that the af frequency has low distortion.

✈ Twin Diode Detector Circuit

DIY Diode RF Detectors

The circuit used here. With two diodes, you can create a voltage doubler. This comes in handy, when the signal to be measured is low in amplitude.

✈ Diode Selection

For RF rectification a fast switching capability is mandatory. In a p–n diode (e.g. 1N4148), the reverse recovery time can be in the order of several µs to less than 100 ns for fast diodes, and it is mainly limited by the diffusion capacitance caused by minority carriers accumulated in the diffusion region during the conducting state.

Schottky diodes are significantly faster, since they are unipolar devices and their speed is only limited by the junction capacitance. The switching time is approx. 100 ps for the small-signal diodes.

 Type Forw. Volt. [mV] Capacity [pF]
 HP 5082-2800 380 2.0
 1N5711 410 2.0
 BAT83S 410 1.6
 1N5712 550 1.2
 HP5082-2811  410 1.2
 HP5082-2835 340 1.0

✈ AM-Demodulator / RF Detector / Demodulator probe for DMM

We use the Twin Diode Detector Circuit here. Assembly : R3 = 51 Ω, C3 = 100 nF, R1, R2 = 51 Ω, D1, D2 = 1N5711, C1 = 100 nF, R4 = 10 kΩ, R5 = 51 Ω.

DIY Diode RF Detectors

The Engineering Sample, mounted in a SucoBox

DIY Diode RF Detectors

Carrier was 1 MHz, + 6 dBm, Amplitude modulated, 40 Hz AF

DIY Diode RF Detectors

Output [mV] vs. Input level [dBm]. Useful for "higher" levels.

DIY Diode RF Detectors

Output [mV] vs. Frequency [MHz]. Level was 0 dBm (blue) and + 10 dBm (orange).

✈ Downloads

✈ Similiar Projects

For a lower level, check out the AD8307 Logarithmic Amplifier
The Levelmod has different sensors as well as an analog output.

✈ Share your thoughts

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t1 = 6586 d

t2 = 191 ms

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