Query on Harmonic Port element in analogLib

Vipul,

In reality the termination is not going to be purely resistive at all frequencies, so being able to enter the resistive and reactive part can be important to better capture the termination. Equally, it's impossible to have a constant complex impedance at all frequencies, so this capability allows you to capture the fact that this impedance will be different at different harmonics of the fundamental. Because this is a frequency domain analysis, we don't have to necessarily have a representation that will be causal in the time domain (which you do for transient analysis) which allows this kind of frequency-domain modelling of the port impedance.

Kind Regards,

Andrew.

(Sorry for posting here, but I couldn't find any way to create my own thread. Maybe the moderator could help me here)

I am trying to simulate the PSRR of an amplifier and estimate how much of the supply ripples are coming to the output. However, I want to see also the transfer function of the mixing products between a 2-tone large signal input and the small signal supply ripples. Therefore, I decided to go with hb/hbxf simulation.
To enable hbxf, I just use hbnoise with Input source set to ‘none’ and ‘Do Noise’ turned off.

As far I can see from the log file, hbxf is calculated and simulation finishes normally without any errors. The problem I see is that ‘hbxf’ doesn’t seem to appear in the ‘’Direct Plot” window? I see only ‘hb_mt’, but not ‘hbxf_mt’.

If I use single tone input with everything else the same, ‘hb’ and ‘hbxf’ are both visible in the ‘’Direct Plot” window. Pss/pxf works also fine with 2-tones.

Edit: I'm using Cadence IC6.1.6-64b.500.13.2


Best Regards,
palmrunner

Palmrunner,

A quick double check before I test this - what IC subversion are you using? (Help->About in the CIW will tell you) and which spectre sub-version (this appears in the spectre log file)?

Regards,

Andrew.

Hi Andrew,

Thanks for your quick reply!
I'm using Cadence IC6.1.6-64b.500.13.2

From the log file I get this: Version 14.1.0.576.isr7 64bit -- 28 Apr 2015

(Miraculously, a button 'New' appeared for me in the community forums. It was missing before :)

Best Regards,
palmrunner

Hi palmrunner,

Having done some experiments and some checks of the CCRs, this has been a long-standing issue with the "xf" being part of hbnoise. The good news is that in MMSIM15.1 together with IC617 ISR3 and later, there is now an explicit "hbxf" analysis on the Choose Analysis form, and if you run a multi-tone HB analysis together with this, you will get "hbxf_mt" on the Direct Plot form. 

It was always an anomaly that if you just wanted to do an hb xf analysis you had to run hbnoise and turn noise off - not a great use model. Unfortunately it seems the original bug (multi-tone xf results not appearing in the direct plot form) has not been fixed in any version, but I think it's far more likely that people will use the explicit hbxf analysis as that's far more logical. 

Of course, to access this you'll need to update to a new enough IC617 release, and also either MMSIM15.1 or SPECTRE16.1 (rather than MMSIM14.1 ISR7 which is what you're using currently).

BTW, the "new" post button being missing was probably a symptom of a sporadic problem at the moment; I have a similar issue that the "rich text" support doesn't always show up and I sometimes have to force reload pages in the browser to make it work (I have a ticket open to try to fix this). As moderator I potentially could split out your post into a new thread - but since we're pretty much done now I'll leave it alone just in case it breaks...

Regards,

Andrew.