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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> Output imepedance https://designers-guide.org/forum/YaBB.pl?num=1314211159 Message started by Rakesh on Aug 24th, 2011, 11:39am |
Title: Output imepedance Post by Rakesh on Aug 24th, 2011, 11:39am Hi, I was working on increasing the linearity of the transconductor. I get a good linearity if i short the output and measure the current. However if i allow a swing of say peak to peak 400mV on the output my linearity goes down to 60dB . My output impedance is 400k. Can u suggest me techniques or ways of increasing the output impedance apart from cascoding. Thanks Rakesh |
Title: Re: Output imepedance Post by harpoon on Aug 24th, 2011, 1:17pm Make L bigger ... Or use feedback, I'll have to think about the circuit. |
Title: Re: Output imepedance Post by loose-electron on Aug 26th, 2011, 10:25am gmC filter transconductor? Prior suggestions are good. Also - Increase the static bias current of the device so the signal is a smaller part of the total current. Also differential pair structures can be replaced with multi-tanh structures as gets used in LNA front ends. |
Title: Re: Output imepedance Post by Vladislav D on Aug 27th, 2011, 4:49am loose-electron wrote on Aug 26th, 2011, 10:25am:
To increase current through the devices in order to increase output impedance? Sounds controversial.... :-/ |
Title: Re: Output imepedance Post by loose-electron on Aug 28th, 2011, 12:17pm He is having problems with linearity vs. output impedance. Thus the suggestion on how to improve linearity. If we know the application a bit more may be able to make better suggestions, I am guessing a gmC filter (4 transconductors per biquad) , but it has not been stated. |
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