How to design 10kHz low pass filter without ext. large caps?

[wylee]

10 khz low pass filter

Recently I faced a big problem on designing a on-chip 10kHz LPF which requires me to integrate everything inside the chip without using any extra IC pads or external capacitors.

Could this be possible?
If 'yes', can anyone give me some ideaw on which architecture I should used? gmC? Sallen-Key type? whatever...

 

[2steps]

10khz lpf

For your case, the filter required is Gm-C Filter

 

[turbocool]

low pass filter 10khz

Yes, but the Gm-C filter has limited dynamic range and may suffer from linearity issues. You may want to use a fully differential transconductor. As well, the capacitor may have to be tuned if you need a very accurate 3dB bandwidth.

For back of envelope calculations: f3dB ~ gm / 2pi C (ignoring parasitics and 2nd order effects)

 

[wylee]

10 khz lpf

so Gm-C filter is the right path to design this right?

Can anyone suggest me some good Gm-C Filter design theory books?

 

[jcpu]

Re: How to design 10kHz low pass filter without ext. large c

                      gm
          10KHz = ----------
                    2 pi C

for C<10pF, gm<0.628uA/V

Any reference / technique to build such small gm cell
with satisfactory accuracy?

Thanks in advance

 

[jfyan]

Re: How to design 10kHz low pass filter without ext. large c

so Gm-C filter is the right path to design this right?

Can anyone suggest me some good Gm-C Filter design theory books?

hi,
the book "design of analog integrted circuits&systens" by laker and sansen, i think, is a good one.
good luck
jeff.yan

 

[arsenal]

try sallen-key LPF, which should be better than gm-c filters since it is an 2nd order filter.