Error when analyzing VCO with HB simulation

[Salahshoor]

i have designed a vco in tsmc 0.18u version2
when i analyze it to obtain phase noise whith hb-simulation it report this problem:



Warning detected by hpeesofsim in frequency search during HB analysis `HB1'.
Circuit is stable. No zero phase crossings of the injected current were
found. For oscillation, a negative going zero phase crossing should exist.
Will try fixed frequency amplitude search.
Error detected by hpeesofsim in arc-length continuation during HB analysis `HB1'.
Value of `HB1_OP.V' went out of range during arc-length continuation.
The range is -999.998 V to 2 kV.
Convergence hints:
o Expand the range with ArcMinValue and ArcMaxValue and re-simulate.
Warning detected by hpeesofsim during HB analysis `HB1'.
Oscillator analysis did not converge. Setting solution to zero.
Warning detected by hpeesofsim during HB analysis `HB1'.
More than one mixing term has landed on frequency 0 Hz.

Status / Summary


hpeesofsim (*) 2008.200 Nov 4 2007 (built: 11/04/07 09:44:20)
Copyright Agilent Technologies, 1989-2007.

HB HB1[1] <<string/GEMX netlist>>
. The circuit appeared to be stable during initial frequency search.
Retrying with a smaller frequency step...

The circuit appeared to be stable during initial frequency search.
Retrying with a smaller frequency step...

The circuit appeared to be stable during initial frequency search.
Retrying with a smaller frequency step...

The circuit appeared to be stable during initial frequency search.
Retrying with a smaller frequency step...

HB_NOISE HB1[1] <<string/GEMX netlist>> noisefreq=(1 MHz->10 GHz) 2 points
..

Resource usage:
Total stopwatch time: 3.95 seconds.

-------------------------------------------------------------------------------
Simulation finished: dataset `vco2' written in:
`I:\Assignments\rf_assignments\osillator_amplifier\ads\vco_prj/data'
-------------------------------------------------------------------------------


---------------------------------------
---- Creating New Display Window ----
---- Please Wait... ----

---- Window Created ----
---------------------------------------










can everyone help me?
i also attach my circuit

 

[Nacl]

Re: help on ads

Your VCO isn't oscillating it looks like. That's why the error says the circuit is stable. That means you don't have any phase noise to measure if it is not oscillating.

 

[Manjularamkumar]

Hi,

I also obtained the same error message for VCO.

If u know to rectify the error, Please tell me.

It is very urgent.