Oscillator design errors in Microwave Office

Hello JMM,

Your problem is different, but the error message is same...!
I think you have good oscillator modelling...But their are couple of things to note & fix they are...
1.
In final Oscillator schematic you have used termination port & trying to access
Nonlinear (Harmonic Balance) measurements such power spectrum etc...
Hence the error...So you need to switch the port to source port (RF Harmonic port)
Then it works fine...
Also change the project frequencies to desired range (instead from DC)....

2. When you want to look at Nonlinear measurements, you need to use spice models for all
the devices (should not use S-parameters specifically for BJT/FET/Diodes)...
If you use any S-parametr files for passive devices (Capacitor/inductor) then try extrapolating
the results upto DC & then use the fils back in Nonlinear circuit schematic for Harmonic balance simulation...

I have modified couple of the above & attached to this...
I hope this helps you..let me know you need any further clarification...

Hello JMM,

Also their are lot of new examples & tutorials on Oscillator design available in AWR Microwave Office 2007 V7.50 /Examples folder...

MWO has some good powerful capabilities for analyzing oscillators (
1. the OSCTEST2 element to break the feedback loop to look for approximate oscillation conditions &
2. the OSCAPROBE is used to determine the nonlinear characteristics of the oscillator).

I have attached couple of AWR MWO oscillator design papers for your reference...
https://www.edaboard.com/viewtopic.php?p=760176#760176

https://www.edaboard.com/viewtopic.php?p=864493#864493

Hello Manju, thank you very much for answering so rapidly. Since you can see my English is bad but I hope that you could understand me.

The project that you sent me does not show the mistake I commented to you, however, when begins the simulation, remains long time simulating 1,1GHz showing messages as " using a reduction of ... dB". Ultimately I despair and finish the simulation. What this one happening?.

Certainly, my name is Javi and I am student of telecommunications Engineering at the University of Cartagena in the south of Spain. The oscillator forms a part of my project end of career. Where are you from?. I would like to know if I can have your help to solve these small doubts that make me lose a lot of time. Only can I speak with you across this web?. Have you e-mail?. It is very important for my to have your help.

Thank you very much for your attention and your help. Regards.

Hello Manju, I am working all day and I have solved the problem that I asked you in the previous message. Now I have to obtain the same results using the block OSC_S of Visual System Simulator. The schematic remains equal as you sent it me but when I introduce it inside the block OSC_S the program shows: could not connect to the oscillator simulator.

Can you help me please?.

Thank you very much again.

Hello Javi,

Yes, their is reason...Read the following
OSC_S imports the characteristics of a Microwave Office (MWO) oscillator design into VSS. The power level, oscillation frequency and phase noise can be obtained from the MWO simulation. The oscillation frequency is determined from the nonlinear simulation at the specified harmonic index while all other harmonics are ignored.
The MWO circuit must contain an oscillator phase noise simulation in order to model phase noise.

One good example on the same available in the following folder can be used to setup..
C:\Program Files\AWR\AWR2007\Examples\Visual_System_Simulator \Phase_Noise\IQ_MOD_PhaseNoise.emp

If you still have the problem...then send me the modified project file...

With Best Regards,
manju

Hello Manju, How are you?.

I write you for I comment to you that I do not manage to simulate correctly the project of the oscillator. To level of circuit (MWO), I could obtain the wished results but now I need to obtain the same results using VSS and the device OSC_S. I have tried it of many forms but it does not work. Can you help me again?.

If I obtain the wished results with this device I will have finished approximately 50% of my project end of career.

Thank you very much again.

Hello Javi,

OK ...Just provide me the Oscillator Frequency Range...
Also do you have 2N5179 device PSpice model, if so then upload it here...
So that it will be easy to guide you complete solution...

Hello Manju,

The oscillator is a project of a classmate of the university. Since I have commented you, my mission is to obtain the same results in VSS. This classmate gave me the project that I have sent you, therefore, I only have the same information that exists in the project and of the simulations realized to level of circuit. I attach the spectrum that approximately must have the oscillator.

As you can see, the oscillator must work at 1296MHz. I′m sorry, but I have not any more information. If you need it, I can ask in the university.

Thank you very much for your interest.

Hello Javi,

Send me the mentioned spectrum plot MWO Oscillator project file....
Please note the earlier sent file is not working or oscillating at the mentioned frequency...

If the MWO Circuit schematic of Oscillator works fine then it is as simple as taking a subcircuit in higher hierarchy system diagram as a block (OSC_S)...
For typical example on the same is the attached one...

Hello Manju

This oscillator will be used as Local Oscillator of the mixers that we need to design the receiver of a radiotelescope that will work to 1420MHz. We need a local oscillator to 1296MHz to obtain a sign to 124MHz after the mixed one. I attach you the following files:

oscilador_manju:This is the first file that you sent me. I have added a schematic VSS with OSC_S but when I simulate it, the program shows the following mistake: could not connect to the oscillator simulator.why?. However, it shows the results of the MWO Circuit Schematic. You can see it in the files "Espectro.jpg" and "Espectro.txt".

In the example that you have sent me, they use the device "OSCAPROBE" but I do not know where to place it inside the schematic. In the project "Oscilador" I use it but the simulator shows the mistake: "Failed to find start-up conditions in the specified frequency range" or "more than one tone not allowed in oscillator schematic".

If you need more information, tell me it please.

A greeting.

Can anyone has the tutorial on MWO introduction manual on how to perform some simple simulation. Thanks!