Differential Amplifier in Cadence doubt

Hi all,

I have a few question about design differential amplifier in Cadence which are:

1. During AC analyze, we will point at one output of the differential amplifier and plot 20dB graph. Does the dB gain indicates 20log (Vout,max - Vout,min) ? Doues Vout,max and Vout,min are in same output point?
2. There are two input port in differential amplifier. Of course, we will give Common mode Voltage at the two input port. What should ac magnitude I should give in these two voltage source for these two input port? 500mV for both inputs or 1V for one input port only? (the purpose to do so is we do not need to recalculate the dB gain based on the gain formula in question 3)
3. Gain = (Vout1-Vout2)/(Vin1-Vin2). What are the Vout1, Vout2, Vin1 and Vin2 refer at the differential amplifier in Cadence?

Jacksoncyh said:

I have a few question about design differential amplifier in Cadence which are:

Click to expand...

I can not understand what you want to mean at all.
Use correct teminology.

Cadence have analog IP development service.
So do you mean differential amplifier IP provided by Cadence ?

It seems your concerns is no more than trivial EDA Tool Play.

Jacksoncyh said:

Doues Vout,max and Vout,min are in same output point?

Click to expand...

I can not understand what you want to mean at all.
What do you want to mean by Vout,max and Vout,min ?

Jacksoncyh said:

What should ac magnitude I should give in these two voltage source for these two input port?

Click to expand...

You can set any values as far as Vin1 != Vin2, since you do linear small signal analysis.
However Vin1=+0.5, Vin2=-0.5 in geneal.

https://www.edaboard.com/showthread.php?t=372232#14

Jacksoncyh said:

3. Gain = (Vout1-Vout2)/(Vin1-Vin2).
What are the Vout1, Vout2, Vin1 and Vin2 refer at the differential amplifier in Cadence?

Click to expand...

I can not understand what you want to mean at all.
Use correct teminology.

https://www.designers-guide.org/Analysis/diff.pdf

Hi,

I am designing differential amplifier by using CMOS, same as this video found in youtube: https://www.youtube.com/watch?v=-BkAKmKYWmE
I am using Cadence tools. During AC analysis, I will swap frequency to determine gain in dB. So, what ac magnitude should be set in both input? I must select one output point to determine the gain. But, formula for the differential amplifier is Gain = (Vout1-Vout2)/(Vin1-Vin2). So, what does dB20 in Cadence indicates during running AC analysis?

Jacksoncyh said:

I am using Cadence tools.

Click to expand...

It does not make sense at all.
Use correct terminologies.

Jacksoncyh said:

During AC analysis, I will swap frequency to determine gain in dB.

Click to expand...

What do you want to mean by "swap frequency" ?

Jacksoncyh said:

So, what ac magnitude should be set in both input?

Click to expand...

Surely read https://www.edaboard.com/showthread.php?t=376105#2

Jacksoncyh said:

I must select one output point to determine the gain.
But, formula for the differential amplifier is Gain = (Vout1-Vout2)/(Vin1-Vin2).

Click to expand...

If you mean your amplifier has only one node as output, Gain is Vout/(Vin1-Vin2).

Jacksoncyh said:

So, what does dB20 in Cadence indicates during running AC analysis?

Click to expand...

What do you want to mean by "in Cadence" ?
I can not understand what you want to mean at all.
Describe correctly using correct terminology.

dB20() = 20*log10()

I don't know what simulator you use at all.
However if you use Cadence Spectre as simulator, run-time-processing such as dB20() is not available during running AC analysis.
dB20() is not available in Cadence Spectre.

You have to do post-processing after running AC analysis, if you use Cadence Spectre.
Can you understand ?

Or do you use Spectre MDL ?
Or do you use other simulator such as HSPICE in Cadence ADE ?
HSPICE has run-time-processing ability.

https://www.edaboard.com/showthread.php?t=354854#10

I am using Virtuoso and I m not sure what simulator. I do this design 1 years ago. I can't remember much about this project. Do u mind tell me the procedure to measure the gain of differential amplifier? I m just curious what I done last year.

Jacksoncyh said:

Do u mind tell me the procedure to measure the gain of differential amplifier?

Click to expand...

Don't use unfamiliar abbreviation.

Jacksoncyh said:

I m just curious what I done last year.

Click to expand...

No one know such thing and have interest.