Rail to Rail input single output symmetrical OTA

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tyanata

Joined: 27 Nov 2003
Posts: 122
Helped: 3
Location: Sofia

11 Dec 2008 16:11 symmetrical type ota

Hi,

Can any one give dvise how to realise rail to rail input single end output symmetrical OTA. I ask for this type of OTA because its best SR performance and Rail to Rail output.

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rfsystem

Joined: 25 Feb 2002
Posts: 858
Helped: 96

12 Dec 2008 20:27 rail to rail symmetrical ota with

That is why Active-RC with an opamp work perfect. There the transconductance is defined by the resistor inputs which are

1. Linear
2. Include the complete supply

If it must be Gm-OTA you must use a transconductance transition where the main operation change from NMOS to PMOS. That is found in some opamp input stages with full input common mode range. The difference is that it should be linear and also the differential signal could reach full supply.

I know the motivation from the kT/C-effect and the power needed to drive low voltage filter.

Scaling has long passed the optimum point for power efficient analog filters.