Help me build a good attenuator for a 100KHz signal

[Ching]

I want to make a attenuator for a 100KHz signal. I built the circuit as showed in the diagram. I find that when I change the control voltage, the signal will attenuate but also be distorted ( e.g. a sin wave input will not give a perfect sin wave output when it is attenuated). Does anyone know how to build a good attenuator?

 

[kronos2k3]

Re: Attenuator?

Hi...

I dont know attenuators with diodes!
I know this attenuator from 1 db to 20 db in all frequency!

See the schematic and find the values in the next table.
The values of the resistance are given for input impedance of 50 Ohms and 75 Ohms.

Best regards from Argentina!

 

[flatulent]

Re: Attenuator?

Your problem is that the diode types are only for very low level signals. You will need to put it earlier on in the signal chain or put a resistive fixed attenuator in front of it and an amplifier following it.

If you are operating below VHF you can use JFETs as attenuators.

https://www.vishay.com/docs/70598/70598.pdf is an application note on how to do this.