Hello,
In the old versions of mmsim (now I'm using the v12) it was possible to set the method used by the initial transient (tstab). How can I set it in mmsim12?
In my simulations transient gives a correct result whereas hb/tstab predicts a strange behaviour that prevents the hb simulation to converge. Which are the default methods of the 2 analysis, tran and hb/tstab? Are there other different settings?
Thank you very much
Best regards
Aldo
Hi,
In PSS form, there is one option called Number of harmonics. I am NOT able to understand what is its use as PSS is any way a Steady state DC operating point analysis ?
Of course, No of harmonics actually controls the time step for better accuracy (like to avoid Aliasing effect etc). But the time step can easily controlled by maxacfreq OPTION.
So my doubt is:- Whether the Harmonic Option in PSS form is needed for Some other reasons ?
IS there any documents which actually explains the need/use (OTHER than controlling Time Step) of No. of Harmonics option in PSS form
Thanks
I have a problem with Flicker phase noise of a quartz crystal oscillator (RLC equivalent cirucit + opamp current amplifier + opamp inverter) simulated with PSS + Pnoise of CADENCE:
Indeed I simulate the phase noise of a quartz crystal oscillator and I include only Flicker noise (verilogA) in the feedback opamp inverter. The simulated phase noise shows white phase noise, f-2 phase noise and f-3 phase noise near the carrier, instead of only f-1 phase noise and f-3 phase noise!
Can you please help me solve this problem?
Best regards
Raphael
Dear All,
I am looking for the latest "Virtuoso Spectre Circuit Simulator User Guide".
While searching in cadence online support it gives me many links with "Virtuoso Spectre Circuit Simulator User Guide xxxxxxxx".
But I am not able to get the exact user guide.
Could anybody please point to the desired link
Kind Regards,
Hello
Initial information - Using Cadence virtusoso 6.1.5-64b & spectre simulator for designing the followingquadrature injection locked frequency tripler.
circuit Diagram -
The first input I gave was a 14.66GHz signal The frequency spectrum of the output is as below:
ANd then I changed the input to a close 14.46G , the output frequency still remains same as shown below.
The core currents of the oscillator(Iosc) and injection current(Iinj) have been optimised such that a locking range of 5% should be there. But in the above case there is no injection locking happening.
Also, I am unsure about the phase noise plot of the QILO . I have put the relative harmonic as 3 as Andrew Beckett suggested in one post. But Cadence is still sweeping it for harmonic -1. I am not sure if it is because of the injection locking not happening and PSS not able to provide the correct 3rd harmonic of the tripler
Can anyone PLEASE PLEASE summarize the setting for the PSS and pnoise (or QPSS or qpnoise) for this type of circuit or check the PSS settings which I have uploaded here :
I have gone through most of the application notes & the solution post for injection locked oscillator.( I made sure as it is a driven circuit I havent selected the oscillator button)
Please guide me through this. Thanks in advance.
Reference paper- A Low Phase Noise Quadrature Injection Locked Frequency Synthesizer for MM-Wave Applications - Musa et al.
Dear all,
An error occurs regarding hidden states when running an AMS envlp simulation:
"ERROR (SPCRTRF-15177): ENVLP analysis doesn't support behavioral module
components with hidden states found in component
'worklib__DataPath__vams__0x10000001_behavioral'. Skipped."
A similar error is raised when using the built-in connect rule E2L_inhconn for example.
I have experimented with the VerilogA attributes (* ignore_hidden_state *), (* ignore_state *) and (* instrument_module *), however they seem to not make any difference, i.e. the same error is raised.
Can somebody confirm that these attributes are ignored in AMS envlp? Is there a workaround besides rewriting the Verilog-AMS code?
spectre version 11.1.0 32bit 08/14/2012 20:55 (usimamd64-23)
irun version 12.10-s005
Best regards
Dear All,
In SpectreRF documents I have come across "Strobed Periodic Noise simulation in SpectreRF" for Synchronous Jitter measurement.
But in Pnoise analysis I have not seen Strobed option.
So what is Strobed Periodic Noise simulation in SpectreRF ?
Kind Regards,
When using mtline model in cadence spectre schematic simulation, why I can not connect output of one mtline to output of another mtline? (warnings show there will be short circuit and floating nodes)
Hi,
I am now working on the delay locked loop simulation. I use a circuit level design for the voltage-controlled delay line, and verilog-a model for the phase detector and charge pump. My target is to simulate the in-band pnase noise (jitter) coming from the delay line will be suppressed compared with open-loop case(not including any noise from phase detector and charge pump). However, this is only observed while I choose the noise type to source, but not the same effect if I choose jitter as the noise type and plot the jee spectrum. Is there any one having the experience on these kind of simulation? I saw that jitter simulation is recommended especially for measuring the jitter for square wave. On the other hand, there are many documents talking about integrate the phase noise to get the jitter. Should the jitter caculation result from different noise type (source or jitter) be consistent to each other?
This is the link to my simulation result plot:
https://docs.google.com/a/berkeley.edu/file/d/0B6zK04zfHkAEZmM3MzJtVkw5MW8/edit?usp=sharing
Thanks,
ycyeh
Hi cadence community,
In designing a power amplifier, what is the purpose of s-parameters of transistor? Incase the manufacturer does not give the s-parameters, how to start designing a power amplifier?
Hi cadence community,
I have to design amplifier with following specs:
Input power = 2.5 W
Output power= 676 W
Gain= 24.33 dB
Frequency = 1030 MHz
I have searched a lot to find transistors for the above specs but didnt get satisfactory lineup.
Can somebody help me find a transistor lineup?
I'm trying to simulate the noise figure of a transmit mixer as a function of input IF power.
From the cadence tutorials it seems as if the HBnoise sim is performed under small signal conditions where the input IF port is set to DC
(for example in http://www.cadence.com/Community/blogs/rf/archive/2011/03/10/tips-for-simulating-a-transmit-mixer-in-spectrerf.aspx, its stated "If you are running PAC or Pnoise, you set the IF sourcetype to dc so that the LO is the only sinusoid in the system (Edit Properties on your IF port in the schematic). Since the input for this example is sinusoidal, we will choose Harmonic Balance. " )
How whould you recommend to perform a noise figure sim with IF signal applied.
In addition when I look at the noise separation print form it shows that the noise of the mixer comes from a biasing circuit which is AC disconnected from the circuit..., this must be an artifact and can not be the real noise source of the mixer, not sure but maybe you have some input on this as well?
Hi,
When using the direct plot option to trace out the PAE (= Pout - Pin / Pdc) after a pss analysis, if the PAE is added to the outputs the formula which gets added to Output window reads as follows :
((100.0 * harmonic ((spectralPower(i("/PORT1/PLUS" ?result "pss_fd") v("/P_out" ?result "pss_fd")) + spectralPower(i("/PORT0/PLUS" ?result "pss_fd") v("/P_in" ?result "pss_fd"))) '(120))) / -harmonic ((spectralPower(i("/V1/PLUS" ?result "pss_fd") v("/Vdc" ?result "pss_fd"))) '(0)))
Here, PORT1 is my output port and Port0 is my input port. P_out and P_in are the output and input nets respectively. 120 refers to the index of the harmonic of interest in my analysis.
Intuitively, I do not understand the following :
Hi all,
yes...there is this support answer #11003524 which should address the topic.
I also learnt from Andrew some time ago about saving oppoints and/or specific info through a file and attaching it to the model libraries.
What I am experiencing now is that the method:
a) gives me the info out of a *tran*
b) gives me the info out of a *envlp_td*
c) for a *pss*, I get
1. a _constant_ value in the *pss_td* folder, if I use the shooting method (seems like a DCOP value)
2. nothing if I use the HB method
Just wondering whether that is the behavior to be expected, or shouldn't I get a (nice) plot of my wanted gm over a period, exactly like I get it for any other V/I in the circuit after a pss?
I seem to remember having done the same thing some 6 months ago and it worked fine..
Thanks for any help.
Michele
Hello All/Cadence Support,
I am having the problem
figuring out how to run IM3 and IP3 simulation if the input file is a pwl file. I
am easily able to run all other analysis of PSS except the IP3. I have
tried PSS+PAC, QPSS which are usual for calculating IP3 but it dont
work. For example,with the PSS+PAC analysis the PAC>IPN Curves has
the message ''The data for each sideband of the pac analysis contains
are frequency sweep.As a result,the above selected function cannot be
executed'.
I need urgent help in this regard!
Hi!
I am trying to simulate a frequency multiplier. The oscillators are simple ring oscillators oscillating at 2GHz made form inverters.What the multiplier circuit is that it cancels the fundamental tone and retains/preservs the 3rd harmonic(3,6,9...) and cancels the other harmoics like 1,2,4,5.......
The problem;
I am interested in looking at the Phase noise at the combiner output oscillating at 6GHz. The output signal has a voltage swing of around 900mV. The setup does not have any ideal blocks in it. In the PSS options form I donot check the oscillator option (I read a post suggesting this in case of a driven circuit, which I assume this multiplier to be)
When I run pss using shooting method it does not converge. I have tried changing the tstab (increasing it), changing the method from trap to gear2 etc. But I can't get the pss to converge (The PSS options form is attached in picture).
When I run PSS using the HB method the pss does converge but the Phase noise at the comes out to +150dbc/Hz which is a unrealistically large value (opposed to the theroratical results).
Running a pss+pnoise for a single ring oscillator works fine. I would be grateful if someone could guide me what could be the problem or if this is the right way of simulating this kind of circuit,
Regards,
MTP
I cannot post the image so here is a link to the circuit diagram
https://www.dropbox.com/s/zb4e5175lyut8sv/FrequencyMultiplier.jpg
Hi,
When I am doing pnosie analysis in cadence spectre (IC 416) , the simulation prematuarly teminated & error flushing like below
Provided I have fixed tstb =200ns for beat frequency = 10MHz
/////////////////////////////////////////////////////////////////////////////////////////////////
pss has reached the maximum iterations (20).
Error found by spectre during periodic steady state analysis `pss'.
pss analysis did not converge. The last unconverged solution is saved.
The following set of suggestions may help you avoid these convergence difficulties.
1. Carefully evaluate and resolve any notice, warning or error messages.
2. Providing a larger value for tstab generally improves convergence. While not always necessary, one occasionally needs set tstab to a value equal or greater than the time needed for the circuit to approximately reach steady state.
3. While trapezoidal rule ringing is annoying in transient analysis, in PSS analysis it can cause the shooting iteration to stall before convergence is achieved. This problem can be remedied by changing the method from traponly to either trap, gear2, or gear2only.
4. Increase the maximum iterations for shooting methods using the maxperiods parameter. Sometimes the analysis may need more than the default number of iterations to converge. However, there are situations that prevent convergence regardless of how many iterations are taken. In this case, increasing the iteration limit simply results in the simulator taking longer to fail.
5. If the shooting iteration approaches convergence and then stalls, it may be because the tolerance on the shooting method is too tight. In this case, try loosening steadyratio, which controls how close to steady-state the result must be before it is declared to be converged.
6. Finally, tightening the normal simulation tolerances (maxstep, reltol, lteratio, errpreset) can help resolve convergence problems in PSS. Avoid using errpreset=liberal.
Analysis `pss' terminated prematurely due to error.
Error found by spectre.
PSS analysis must be executed before pnoise. Analysis skipped.
Analysis `pnoise' terminated prematurely due to error.
modelParameter: writing model parameter values to rawfile.
element: writing instance parameter values to rawfile.
outputParameter: writing output parameter values to rawfile.
designParamVals: writing netlist parameters to rawfile.
primitives: writing primitives to rawfile.
subckts: writing subcircuits to rawfile.
Can help someone regarding this issues.
I'm trying to simulate a simple passive LRC resonator circuit (https://www.dropbox.com/s/nlzpv9b9gvtceca/Untitled.png), i get results as expected from AC and transient sim (resonance at 10 MHz) but can't get HB to work. it seems that no matter what settings I choose, i have the error:
V(resonator) is too small to reliably detect the period of the oscillator.Perhaps nodes with insignificant signal levels were chosen, or perhaps the oscillator was never properly started.
