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Simulators >> RF Simulators >> problems of sc filter
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Message started by adelezy on Jun 17^th, 2010, 7:44pm

Title: problems of sc filter
Post by adelezy on Jun 17^th, 2010, 7:44pm

Hi, All

I simulated one sixth-order elliptical Low-Pass SC Filter.
The example that I used is <Demystifying Switched-Capacitor Circuits> MingLiang Liu P101

In the circuit, ideal opamps and switches are used.
OP's gain, UGBW and slew rate was considered and checked.
The switches' on resistor is set to 1ohm.
PAC simulation result is that 0db in pass band and w-3db is also right, but probelm exists in tran analysis.
The amplitude of sine wave is much smaller than input, and the output attenuation is about -5db.
The other problem is that output wave is like saw wave, not sine wave.

Thank you.

Title: Re: problems of sc filter
Post by Mayank on Jun 17^th, 2010, 9:02pm

Quote:

The amplitude of sine wave is much smaller than input, and the output attenuation is about -5db.

Are you using the same termination as you were using while doing PAC analysis ??

Quote:

The other problem is that output wave is like saw wave, not sine wave.

Is the Opamp Slewing instead of linear settling ?