How to design rail-to-rail input and output bipolar op-amp?

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staric

Joined: 26 Sep 2003
Posts: 80
Helped: 1

29 May 2005 10:20 How to design rail-to-rail input and output bipolar op-amp?

Need to design a rail-to-rail input and output bipolar op-amp. The open loop gain is 120dB. And the fT is 8MHz. I think it is a difficult design. Who can give me some suggestion or reference? Thanks.

yeechyan

Joined: 14 Jun 2004
Posts: 111
Helped: 1

30 May 2005 13:36 How to design rail-to-rail input and output bipolar op-amp?

Some infos available from this link:

www.ee.nthu.edu.tw/~hchen/pubs/20op.pdf

rhesusmonkeyboy

Joined: 01 Jun 2005
Posts: 8
Helped: 2

01 Jun 2005 18:54 One way is to essentially have 2 op-amps in Parallel

I recall doing this in grad school. I don't have my textbook with me.

Doing a Yahoo search on "rail to rail" pnp npn input output yielded this PDF which is a more clever version of what we did: entitled "Low-Distortion High-Speed Rail-to-rail Input/Output Amplifiers" from Analog Devices

If I remember when I get home, I can point you to a specific chapter in a book as well.

Note: You end up having a region with a peak in gm ( transconductance )

Note: I'm unable to link to the Yahoo search page, as well as the PDF in question.

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nafaiz

Joined: 18 May 2005
Posts: 106
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Location: Malaysia

01 Jun 2005 23:12 Re: How to design rail-to-rail input and output bipolar op-a

a very good journal

http://www.edaboard.com/viewtopic.php?t=120636&highlight=

karthik167

Joined: 17 Feb 2005
Posts: 6

02 Jun 2005 22:53 Re: How to design rail-to-rail input and output bipolar op-a

try to get hold of book Analog VLSI: Signal and Information Processing by Ismail and Fiez, McGraw Hill, NY, 1994. Also some of his publication esp ieee jssc vol 31, 1996

hope it helps

karthik

rhesusmonkeyboy

Joined: 01 Jun 2005
Posts: 8
Helped: 2

03 Jun 2005 2:18 I meant to add

I meant to add, essentially you have 2 "transconductance" opamps, OTA, set up in parallel, an NMOS input and a PMOS input type, with wide swing outputs.

A picture ( difficult to understand in my opinion ) can be found on page 287 of the Johns and Martin book"Analog Integrated Circuit Design" published by Wiley.