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Comparision of SC filter and GmC filter in audio frequency

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hebu

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sc filter

In IC implementation and audio frequency application. SC or GmC has the
better dynamic range?
Consider the flicker noise, thermal noise, linearity. And, the filters are same
type.
 

gm-c filter

hebu said:
In IC implementation and audio frequency application. SC or GmC has the
better dynamic range?
Consider the flicker noise, thermal noise, linearity. And, the filters are same
type.
Click to expand...

Hallo Hebu!

SC is the much better choice! SC has better linearity, the flicker and low frequ. noise can be cancelled using correlated double sampling or choppering. With SC you can just get DR as high as 120dB, while gmC has mabye the half!
 

gm-c filters

Usually, what's the clock frequency in audio application?

How I define the requirement of clock frequency, anti-aliasing filter, and smoothing filter?

Thanks,
 

noise in sc filter

the audio frequency is not larger than 192k( in general it is 48k), so the clock frequency just rely on the oversampling ratio in you system. 12.288M is usually used frequency.
 

sc filter

If we want to make a Req such as 1M ohms high, Req=T/C.
And the clock freq is as high as 10MHz, the C should be 0.1pF.
Is this realiable size in 0.35um IC implementation?
Or, anything I missed?
 

gm-c filter latest application

hebu said:
If we want to make a Req such as 1M ohms high, Req=T/C.
And the clock freq is as high as 10MHz, the C should be 0.1pF.
Is this realiable size in 0.35um IC implementation?
Or, anything I missed?
Click to expand...

Yes, 100fF is no problem. BUT the noise (= k*Temp/C) may be to large.

I would say caps like 1pF is more suitable.
 

filter sc gmc

hebu said:
If we want to make a Req such as 1M ohms high, Req=T/C.
And the clock freq is as high as 10MHz, the C should be 0.1pF.
Is this realiable size in 0.35um IC implementation?
Or, anything I missed?
Click to expand...

100fF is already the minimum value of mimcap for 0.18um CMOS
I think for 0.35, maybe it is higher, you may check it easily

for smaller value, you can put capacitor in serial or using MOS dummy cap
but the accuracy degraded, I think this is fatal for analog filter...
 

what is gmc filter

Two questions,
1. how about the 100fF cap to tolerate the charge injection?
2. If a switch cap ckt needs to be made a precise matching between 0.5fF and
50pF, is it possible?
 

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