is it the correct topology for iout??

[muffassir]

Hi ,

In my circuit i have output currents as Iout1 and Iout2 from two places.What i want is Iout=Iout1-Iout2.
This is my circuit for this.I urge you all to correct the circuit if it is wrong .I have used current mirrors as shown in the image.



will this ckt will give me the desired output.

 

[erikl]

will this ckt will give me the desired output.

Not exactly: ;-)

• Necessary condition to measure current between output & gnd: Iout2 > Iout1
• w(P1) ≠ w(P0)
• the source/bulk nodes of all pmosfets seem to be not connected to vdd (no wire name visible)
• V7 is unnecessary
• With your vout - R0 combination you destroy your result. Use a current probe or a cccs element + resistor (or current probe) instead.

 

[muffassir]

Not exactly: ;-)

• Necessary condition to measure current between output & gnd: Iout2 > Iout1
• w(P1) ≠ w(P0)
• the source/bulk nodes of all pmosfets seem to be not connected to vdd (no wire name visible)
• V7 is unnecessary
• With your vout - R0 combination you destroy your result. Use a current probe or a cccs element + resistor (or current probe) instead.

Hi erikl ,

Well the ckt shown in the image is not the actual ...i have redrawn it..since it is a part of a big circuit..so ur second and third point (coorected) is

2) the widths are sAME ...

3) they are properly connected to vdd.(its my mistake of not drawing it properly here,original ckt is as per the rules)
4) V7 is neceesaary to me since i am going to use the ckt below threshold so i will connect there -0.5 V for vss.

in your last point u said to connect cccs + resistor.. Thanks for the suggestion..Further what according to you should be the
value of resistor for measuring the currents around of 5nA. and
the current gain be of cccs as 1 is enough or not.

Thanks a lot..

 

[erikl]

what according to you should be the value of resistor for measuring the currents around of 5nA.

To measure a current, actually you don't need a resistor at all: Use an iprobe element (analogLib) and probe one of its terminals.

the current gain be of cccs as 1 is enough or not.

Whatever you want. With gain=1 you don't have to recalculate.

 

[checkmate]

Iout1 gets mirrored twice. Why not get rid of the mirrors and connect it directly to the output?