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Design >> Analog Design >> Balun hspice netlist
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Message started by GiangHu on Nov 13^th, 2004, 9:23am

Title: Balun hspice netlist
Post by GiangHu on Nov 13^th, 2004, 9:23am

Hi Ken,

The balun netlist that you posted in diff testbench
should be read as below:

The gain=0.5 not 2, if no "transformer" is included.

.subckt balun vid vic vi+ vi-
E1 5 vic vid 0 0.5
v1 vi+ 5
F1 vid 0 v1 0.5
r1 vid 0 1T
E2 6 vi- vid 0 0.5
v2 vic 7
F2 vid 0 v2 0.5
r2 7 6 1u
.ends balun

Thx
GiangHu

Title: Re: Balun hspice netlist
Post by eskiyerli on Dec 31^st, 2004, 8:52am

I had noticed the same thing. Ken gracefully changed the netlist. However, I still have my doubts about that circuit. I am getting strange results for S parameters. I think the problem is that the model is not truly reciprocal.

Regards,

Murat Eskiyerli

Title: Re: Balun hspice netlist
Post by Ken Kundert on Dec 31^st, 2004, 9:28am

Can you quantify the problem. Say by analyzing some ideal circuits for which the S-parameters are known, and then contrasting the results you get versus the results you should get?

-Ken

Title: Re: Balun hspice netlist
Post by Ken Kundert on Jan 2^nd, 2005, 4:12pm

Guys,
I've tracked down a second problem: the gain of the current controlled current sources should be negated. Here is the updated netlist:

Code:

* BALUN
*
* A bidirectional balanced-unbalanced converter.
* Maps between the unbalanced signals ‘d=1’ and ‘c=2’ and the balanced signals ‘p=3’ and ‘n=4’.
.subckt balun (1 2 3 4)
* Ideal transformer for the positive input
E1 5 2 1 0 0.5
V1 3 5
F1 1 0 V1 –0.5
R1 1 0 1T
* Ideal transformer for the negative input
E2 6 4 1 0 0.5
V2 2 7
F2 1 0 V2 –0.5
R2 7 6 1u
.ends balun

I have updated the paper on the site. Thanks for pointing out these problems.

-Ken

Title: Re: Balun hspice netlist
Post by eskiyerli on Jan 7^th, 2005, 9:29am

Thanks Ken,

I knew there was a problem as the I was getting 6dB S11 instead
-6dB at the input, but was too tired to track it.
Now, it seems to be working nicely.

Thank you,

Murat

Title: Re: Balun hspice netlist
Post by eskiyerli on Jan 7^th, 2005, 9:57am

I made a mistake in the earlier post. What I meant was that ac signal
at the input was +6dB instead of -6dB when matched.

Murat