RF Design - All Comments

Is there a step by s ...

RizwanAhmed — Thu, 05 Nov 2009 21:53:06 GMT

Is there a step by step tutorial about "how to simulate divde-by-2" ?

I have not run this ...

BunnyMan — Sun, 18 Oct 2009 17:52:57 GMT

I have not run this module, but from what I've read here, I agree with Kevin’s comments in that as much documentation as possible should remain on the schematic. This would make it easier to review and update both the design & test attributes together. I would also like to see the program read in the variables. Then, allow active test changes and document the final test parameters if any. Indeed, this is a great start (keep going!). I look forward to seeing any future updates.

A very good example ...

Frank Wiedmann — Thu, 08 Oct 2009 08:42:09 GMT

A very good example that shows how useful pstb analysis is for simulating the stability of DC/DC converters can be found at www.cadence.com/.../CD12_WerthT_iasrwth.pdf .

Hi Shail, I'm not ...

Anonymous — Mon, 21 Sep 2009 17:56:34 GMT

Hi Shail, I'm not sure what you mean by "wasn't able to find a download link to spectreRF". If you want to download the software, you go to downloads.cadence.com and download MMSIM 7.1 (for example). SpectreRF is included in the MMSIM stream.

best regards,

Tawna

hi all well i wasnt ...

Anonymous — Sat, 19 Sep 2009 02:13:57 GMT

hi all well i wasnt able to find a download link fo spectreRF can u plz send me the link or post it here...

thanks

shail

Hi mmwave, rfTlin ...

Tawna — Sat, 29 Aug 2009 00:29:40 GMT

Hi mmwave,

rfTlineLib is located in the IC5141 cds hierarchy at /path_to_cds/tools/dfII/samples/artist/rfTlineLib

Note that rfTlineLib is not yet supported in IC6.1.3, but will be in the future.

best regards,

Tawna

Where is rfTlineLib ...

mmwave — Fri, 28 Aug 2009 00:58:41 GMT

Where is rfTlineLib located? Just couldn't find it.

You could try to do ...

Frank Wiedmann — Mon, 24 Aug 2009 09:28:45 GMT

You could try to do a frequency sweep relative to the first harmonic. However, this does not seem to be possible for PSTB, at least not via ADE. You can still try a PAC simulation instead. Because your break point has a low output impedance and high input impedance, you can put a PAC source in series and calculate the loop gain as the (negative) ratio of the PAC amplitudes on both sides.

Thank you for the in ...

Anonymous — Thu, 06 Aug 2009 20:32:41 GMT

Thank you for the information. However, this is just a start. I really wish that most, if not all control of simulations and variables could be defined on the schematic rather than in the ADE interface.

Design variables, measurements, analysis and schedule/sweep functions should be definable on the schematic to add clarity to the test definitions and measurements.

There is nothing better for clearly transmitting the intention of a test and measurements than a well organized schematic with the critical parameters defined on the schematic Granted there are tests with too many parameters and analysis, but ADE XL is helpful when things get too complicated.

I have a current mod ...

Anonymous — Wed, 29 Jul 2009 12:44:09 GMT

I have a current mode DC-DC converter which has two feedback loops. The only place a iprobe can be placed which breaks both loops is essentially between the comparator and pass transistor, however PSS/PSTB doesn't seem to handle breaking the loop at a purely digital spot. Is there a way around this?

Greg, Sorry fo ...

Anonymous — Fri, 17 Jul 2009 16:56:52 GMT

Greg,

Sorry for the delay in replying, I have been at CDNLive! Japan this week.

It was fun but hectic!

The issue is that the syntax example from the bipolar ft testbench is the

syntax for the bipolar ft schematic testbench simulation. In the testbench

schematic, the DUT is called Q0. In this netlist, the DUT is NM0. So the

correct syntax would be

dB20(i("NM0:d" ?result "ac-ac")/i("NM0:g" ?result "ac-ac"))

which matches the format used in the save command.

Also as mentioned in the bipolar append, it is easiest if you actually

build the expression yourself rather than trying to remember the syntax.

For example, if you are using ViVA:

1. Open the Results Browser

2. Select the output data directory, raw/psf/...

3. Select the results, ac-ac

4. Right mouse button on NM0:d and select calculator

5. Right mouse button on NM0:g and select calculator

6. Select divide, "/" from the calculator keypad

7. Select, dB20 from the "Math" functions

Also, just noticed that there is a typo in the bipolar portion of the netlist.

The probe and the instance name are mismatched. The issue can be

resolved by renaming the instances,

simulator lang=spectre

global 0

parameters ICE=100u VCE=5

// these model files should be available in the samples directory

include "./models/NPNlower.scs"

include "./models/cornerMos.scs" section=TNTP

V0 (net014 0) vsource dc=VCE type=dc

// MOSFET ft

// NOTE: the element instance names have been changed

// the default names are shown in the bjt section

// IREFERENCE --> 0V voltage source

// IFEEDBACK --> current-controlled, current source

IIN (net014 net9) isource dc=ICE mag=1 type=dc

IREFERENCE (net6 0) vsource dc=0 type=dc

IFEEDBACK (net9 0) cccs gain=1.0 probe=IREFERENCE

NM0 (net014 net9 net6 0) nmos24 w=24u l=1.5u m=10

// BJT ft

IIN_BIPOLAR (net014 net025) isource dc=ICE mag=1 type=dc

IREF_BIPOLAR (net012 0) vsource dc=0 type=dc

IFDBK_BIPOLAR (net025 0) cccs gain=1.0 probe=IREF_BIPOLAR

Q0 (net014 net025 net012 0) NPNlower

ac ac start=1 stop=100G annotate=status

save NM0:g NM0:d Q0:c Q0:b

Best Regards,

Art Schaldenbrand

Hi, i tried to simul ...

Anonymous — Thu, 16 Jul 2009 03:54:19 GMT

Hi, i tried to simulate ft of the mosfet.

I tried to rebuild the circuit you list and plot it.

dB20(IF("/M0/D")/IF("/M0/G"))

And it show a error. it can handle nil / nil.

Can you tell me how to simulate correctly? Thanks.

1) Save the collecto ...

Art3 — Wed, 24 Jun 2009 01:29:07 GMT

1) Save the collector and base currents

2) First calculare beta.

In the calculator, divide ( collector current / base current), make sure you use the

the ac currents for the calculation:

i("/Q0/C" ?result "ac-ac") / i("/Q0/B" ?result "ac-ac")

3) Use the cross function to find the frequency when the current gain is 1

or you can convert the expression into dB20 and look for the zero crossing

cross(dB20((i("/Q0/C" ?result "ac-ac") / i("/Q0/B" ?result "ac-ac"))) 0 1 "either" nil nil)

Best Regards,

Art Schaldenbrand

Hi Art, How do yo ...

Anonymous — Mon, 22 Jun 2009 16:00:04 GMT

Hi Art,

How do you plot fT vs IC as in Fig. 7?

Thanks

Subzero, IFEEDBAC ...

Anonymous — Tue, 09 Jun 2009 14:44:41 GMT

Subzero,

IFEEDBACK is a current-controlled, current source, cccs, in analogLib. The plot

shows the ac beta --> i_collector/i_base, where the lower case i is meant to show

the ac current.

If you would like the netlist for the testbench, you can find it at the following link,

www.cadence.com/.../simulating-mos-transistor-ft.aspx

Best Regards,

Art Schaldenbrand