Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

op-amp gain problem ?

Status
Not open for further replies.

farshadr

Newbie level 6
Joined
Mar 1, 2011
Messages
12
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,357
hi
what name is this opamp ?
i need to calculate Gain and Rout and Rin of circuit.
please help me, this is emergency.
so thanx
untitled12121.JPG

Image View
 

jardila

Junior Member level 2
Joined
Sep 17, 2009
Messages
23
Helped
3
Reputation
6
Reaction score
2
Trophy points
1,283
Location
Colombia
Activity points
1,416
Hi,

I don't know its name, but is a basic topology with two stages of gain.

Gain = (gm1gm6/gm3)(ro6||ro8)

Rin = inf.

Rout = ro6||ro8

If you need a more extended explanation about how I obtained these results, you can ask me again.

PD: I assume gm1=gm2 and gm5~8 are equal.

Best Regards.
 
Last edited:

leo_o2

Advanced Member level 4
Joined
Sep 3, 2004
Messages
1,324
Helped
277
Reputation
556
Reaction score
241
Trophy points
1,343
Location
China
Activity points
5,761
I would like to correct the gain equation:
Gain=gm1.(ro6||ro8)
 

permute

Advanced Member level 3
Joined
Jul 16, 2010
Messages
923
Helped
295
Reputation
590
Reaction score
268
Trophy points
1,343
Activity points
8,543
That is a "miller ota".
 

dgnani

Advanced Member level 1
Joined
Jul 25, 2009
Messages
425
Helped
160
Reputation
322
Reaction score
152
Trophy points
1,323
Location
USA
Activity points
4,007
The correct DC gain of this OTA is:
(gm5/gm3)gm1(ro6||ro8)

I guess leo_o2 assumed gm5=gm3 but this does not have to be
 

leo_o2

Advanced Member level 4
Joined
Sep 3, 2004
Messages
1,324
Helped
277
Reputation
556
Reaction score
241
Trophy points
1,343
Location
China
Activity points
5,761
Yes. I supposed gm5=gm3.
dgnani is correct.
And it is one gain stage OTA.
 

jardila

Junior Member level 2
Joined
Sep 17, 2009
Messages
23
Helped
3
Reputation
6
Reaction score
2
Trophy points
1,283
Location
Colombia
Activity points
1,416
Yes I made a mistake, sorry!, but I edited the post and fixed the error.
Thanks for the observation.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top