Continue to Site

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.

Register Log in

Question about simulation ICMR (input common mode range)

Status
Not open for further replies.
C

chungming

Full Member level 1
Joined
Mar 23, 2006
Messages
96
Helped
3
Reputation
6
Reaction score
0
Trophy points
1,286
Activity points
2,041
icmr input common mode range

Hi ~~
If I have a two stage single ended differential amp, and the input is rail to rail (has NMOS & PMOS as input stage), but output is cascode configuration (two nmos cascode & two pmos cascode).
When simulation ICMR we often use unit gain configuration, connect Vin- to Vout so Vin- = Vout, then sweep Vin+.
Vin can rail to rail, but Vout can’t … The ICMR will limit by output swing.
How to simulation real input common mode range ??
Thanks !!
 

Use second amplifier (e.g. ideal voltage controlled voltage source, vcvs) with gain=1. vcvs in+ connect to output of amplifier Vout, in- connect to some fixed voltage e.g. Vdd/2. Connect output of vcvs out+ to Vin-, out- to Vin+. Now you still have unit gain configuration but Vout won't change with ICM voltage and can apply any ICM level as you want.
Note. The output of vcvs will equal to offset voltage.
Good luck
P.S. I've just found you already got this topology "from cadence white paper" in parallel post.
 
Hello. I'm very sorry for bumping this really old thread. But it turns out it has the best explanation I've been able to find regarding icmr testing.
The results using this are great, but I'm afraid I don't fully understand how exactly is it that the output swing is left out of the equation using these.
Could someone please explain this a little bit better?
Thanks to everyone in advance.
Regards,
Ismael
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top