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Simulators >> Circuit Simulators >> "bandwidth" calculation
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Message started by wave on Jul 11^th, 2011, 4:54pm

Title: "bandwidth" calculation
Post by wave on Jul 11^th, 2011, 4:54pm

Hello - I have a bandpass filter, simulated with an AC response.
I'm using Cadence IC615, and in the calculator trying to get the -3dB points for both HPF and LPF corners.

It's a very clean filter passband (no ripples), and clean roll-offs (no P-Z doublets, etc.)

The AC sim is done well before the HPF corner and well *after* the LPF -3dB corner.

The calculator either
a) gives me an Error \n, does not evaluate waveform,
or
b) calculates one side (ie, low or high), but gives a very wrong result.

Any tricks??

thanks,
Wave
:-?

Title: Re: "bandwidth" calculation
Post by wave on Jul 12^th, 2011, 1:26pm

In case more detail helps, the Calc function is:
bandwidth(dB20(VF("/sim_node2")) 3 "low")

Title: Re: "bandwidth" calculation
Post by kokabanga on Jul 13^th, 2011, 8:40am

bandwidth(VF("/sim_node2") 3 "low")

Title: Re: "bandwidth" calculation
Post by wave on Aug 29^th, 2011, 2:51pm

I finally looked at this again.

I think the issue is I have a BandPass response (HPF + LPF).
So "high" and "low" (pass filters) key off of the DC gain, which doesn't exist.

There is a "pass" function that measured the LPF-HPF 3dB point;
However, that tells me the BW between the points, not what Frequency the points are at.

I really need to:
measure MAX passband gain.
Then measure -3dB at a Higher Freq from Max frequency.
Then measure -3dB at a Lower Freq. from Max frequency.

Title: Re: "bandwidth" calculation
Post by sheldon on Oct 9^th, 2011, 2:08am

Wave,

For what it is worth bandwidth works for me.

Best Regards,

Sheldon