The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Mar 28th, 2024, 4:38am
Pages: 1
Send Topic Print
Cadence IC5.1 and MMSIM10.1 (Read 691 times)
Naga Kishan
New Member
*
Offline



Posts: 4

Cadence IC5.1 and MMSIM10.1
Aug 19th, 2015, 12:32pm
 
Hi,

I am using Cadence IC5.1 with MMSIM10.1 and simulating for phase noise using PSS/Pnoise analysis.

The simulation runs well for PSS, but it shows 2 warnings as shown below for Pnoise:

1) Warning from spectre at freq = 100 MHz during PNoise analysis `pnoise'.
   WARNING (SPECTRE-16518): Arithmetic exception in analysis `pnoise' .
..
2) Warning from spectre at freq = 1 Hz during PNoise analysis `pnoise'.
   WARNING (SPCRTRF-15037): Infinite flicker noise is ignored.

I will be obliged for your help.

Regards,
Naga
Back to top
 
 
View Profile   IP Logged
Naga Kishan
New Member
*
Offline



Posts: 4

Re: Cadence IC5.1 and MMSIM10.1
Reply #1 - Aug 20th, 2015, 1:22pm
 
Hi,

I am using the following specifications to calculate the CMOS ring oscillator (Inverter-5stage)

PSS
Engine: Shooting
Fundamental frequency 3.1GHz
Number of Harmonics 64
errpreset: moderate
tstab: 333ns
Oscillator . clk, gnd!

pnoise
sweeptype. relative
relative harmonic: 1
output frequency sweep range: 100K - 100MHz
sweep type: log
points per decade: 200
Maximum sidebands - 64
output - voltage - clk, gnd!
Noise type - sources
Noise separation - yes

I get the below attached phase noise value.

So, my main questions are:

1. Does this plot look reasonable?

2. what should be the phase noise value for a best ring oscillator (or in a range of dBc/Hz)

3. It is used for a divider circuit which CML logic which uses differential clocks ( clk and clkb ), so i designed with a inverter at the output of the oscillator. So, my question is does the phase noise differ for clk and clkbar (complement). does i need to use clkb for reference node in both pss as well as pnoise.

Thanks for your quick reply in advance.

Back to top
 

PHasenoise_clk_3_1G_-42dBc.png
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2024 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.