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.

How do you simulate differential s parameters using LSSP?

Status
Not open for further replies.

iVenky

Advanced Member level 2
Joined
Jul 11, 2011
Messages
584
Helped
37
Reputation
76
Reaction score
35
Trophy points
1,318
Location
College Station, Texas
Activity points
6,124
I am trying to figure out the s-parameters of a push pull class B power amplifier, but the problem is that the input is differential. I am allowed to enter only one input port on the LSSP window in Cadence Virtuoso when I actually have two ports at the input (one for positive terminal and other one for negative terminal which as a phase difference of 180 with respect to the positive terminal). How do you plot differential s-parameters in this case?
I have attached the schematic for better understanding.
class_b_amplifier.JPG
 

I'm not expert in what you're doing but it appears you're expecting results for one system, yet your setup contains two systems (a differential amplifier and a class B amp). Or does your setup have a differential amplifier producing two signals, which are fed to two halves of the class B? OTOH if they are mirror images of each other, then I believe you can simplify operation so it only tests a class B amplifier. I think this means you arrange the layout so it only applies one input signal.
 

I am allowed to enter only one input port on the LSSP window in Cadence Virtuoso when I actually have two ports at the input (one for positive terminal and other one for negative terminal which as a phase difference of 180 with respect to the positive terminal).
LSSP in Cadence ADE simply invoke two one-tone-PSS(Shooting or HB) for forward and reverse direction.
One is for forward direction.
The other is for reverse direction.

Don't use Cadence ADE blindly without understanding background theory.
And equations in Cadence ADE have many mistakes especially for RF.

Don't use LSSP.
Simply do one-tone PSS.
If you can understand S-parameters definition, reference impedance concept and differential/common modes correctly, you can evaluate anything.

If you need only forward direction characteristics, two PSS are not required.

In differential DUT, characteristics measures are sixteens :
S11(DD), S12(DD)
S21(DD), S22(DD)

S11(DC), S12(DC)
S21(DC), S22(DC)

S11(CC), S12(CC)
S21(CC), S22(CC)

S11(CD), S12(CD)
S21(CD), S22(CD)

However, your schematic is configured for only differential output mode.
So you can not evaluate DC and CC.

https://en.wikipedia.org/wiki/Scattering_parameters#4-Port_Mixed-Mode_S-Parameters

If you require only DD characteristics, use one port for differential input same as output port.
Or use rfLib/balun or rfLib/balun_com.
I don't recommend analogLib/ideal_balun

See https://www.edaboard.com/threads/352410/
 
Last edited:
  • Like
Reactions: iVenky

    iVenky

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top