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RF Signal Attenuator up to 30dB for 1MHz - 500MHz Input
This is a PIN diode based RF signal attenuator circuit operates with 1MHz – 500MHz input. PIN diodes are one of the most common parts used in RF applications generally as switches in transmitter and receiver circuits. They are usually placed at antenna or amplifier parts. In some applications PIN diode functions not only as switch but also only as potentiometer.
Resistance of PIN diode is high when no current passing through it. When current starts flowing, resistance decreases and diode conducts. In this circuit we use PIN diode as a potentiometer. You can use this circuit in a wide variety of applications. Some examples;
- Level control in signal generators
- Regulation of antenna signal at receivers
- Power control in RF amplifier drivers
- AGC control at receivers
- Operating frequency range: 1MHz – 500MHz
- Input – Output impedance: 50ohm
- Supply: +5V, 0…+5V
- Insertion loss: <2.5dB
- Attenuation: -10dB, -20dB, -30dB
There is two voltage supply at the circuit. One of them is constant +5V. The other one V(var) is regulated voltage between 4V-5V. You can see attenuation values against V-Var voltage.
You can use a multiturn potentiometer connected to +5V for V-Var adjustment.
Circuit can be used only for less than 100mW powered 1MHz-500MHz input signals!