Recent content by rfonboard

Tnanks! I did try the air core coil used for speaker crossover. The distortion was still bad. Finally I got the idea that the distortion was caused by the 1 uF ceramic chip capacitors used in this filter. It seems that at such a low frequency the dielectric material of the caps has a high...

I discussed this problem with an enginner from Coilcraft. I thought this distortion might still be caused by the saturation distortion of the inductor. It seemed that the ferrite core used for inductor would not work well at such a low frequency. I am going to try the inductor built with either...

Right now, the problem is the harmonic distortion. With 1V pk-pk fundamental signal, the harmonics are way way higher than the noise floor. They suppose to be less than the noise floor.

You are right. Shielding will help for 110 dB attenuation. But at this frequency it should be very easy to achieve 90 to 100 dB attenuation. It did not gete close to it and the harmonics out of the filter were much higher than the input. Talking with the inductor manufacturer, I know the...

Sorry! I thought my post weren't updated.

The filter is designed to filter out the harmonics of 5KHz, which are 10KHz and 15KHz. Since the harmonics of 5KHz signal from the synthesized generator are -80 dBc relative to the fundamental, through this filter, the harmonics should be -110 dBc, which should noe be observed by using a...

I have tried all kinds of active filter, like Chebychev, Multi-feedback, GIC, GIC elliptic, etc. Even the distortion performances of some OP AMP can be -120 dB in data sheet, once built in filter, the harmonic distortion can not be better than -80 dBc. Active device normally be more distortable...

The filter is designed to filter out the harmonics of 5KHz, which are 10KHz and 15KHz. Since the harmonics of 5KHz signal from the synthesized generator are -80 dBc relative to the fundamental, through this filter, the harmonics should be -110 dBc, which should noe be observed by using a...

I am trying to build a 5KHz passive elliptic LPF for harmonic supression. The problem was that the 1.2mH axial high current inductor caused a severe harmonic distortion. The frequecy response was exactly as it supposed to be designed. But the filter introduced higher harmonics rather than to...