Error in ADS: Cannot increase oscport level to set loop gain to 1.

[Sadegh.j]

Hey again

What does this error mean:

Error detected by hpeesofsim in level search during HB analyses 'HB1'.
Cannot increase oscport level to set loop gain to 1.

The circuit that I am analyzing is the one given in www.RFic.co.uk and is attached.

The model is BSIM 3.

Shot

 

[khouly]

Error in ADS

in ur schematic the VSS ic as VDD not even reverse polarity how this circuit will work

khouly

 

[Sadegh.j]

Re: Error in ADS

Hey dude!

Vss is -Vdd, I know, it is a bit tough to see the minus sign, just zoom in a bit please.

Shot!

 

[khouly]

Error in ADS

try to put the osciport in serise with the tank coil

if not work , try to increase the current

khouly

 

[Sadegh.j]

Re: Error in ADS

Funny stuff Khouly!!!

I decreased the current source and it started oscillating, I am thinking about the reason, interesting, isn't it?

 

[khouly]

Error in ADS

wow , it is interesting , can u send me the project to check it

khouly

 

[Sadegh.j]

Re: Error in ADS

Definitely, I'll attach it.

Now that I am thinking, it kind of make sense because as you decrease the value of the current source, the overall gain increases. (since ro increase). so may be the loop gain gets a chance to become unity.

I doubt the conclusion, but it kind of makes sense, I am right?

 

[Sadegh.j]

Re: Error in ADS

sorry, forgot to say, change the current source to 1.5 mA.

 

[khouly]

Error in ADS

i have checked the circuit , when i just make it single supply VSS= 0 , and VDD = 3 V , it oscillate and everything id going ok , even when the current source is equal to 3.5 mA

 

[ADS_RFMW]

Re: Error in ADS

What exactly you want?

 

[Sadegh.j]

Re: Error in ADS

Hey

It's just a course project. Design an oscillator to get some specs. I decided to change an already designed oscillator.

Added after 38 seconds:

Khouly, why do you think it's like this?

 

[khouly]

Error in ADS

i don't know , but i have never used a daul supply ,

we can ask some experts here :s

khouly

 

[Sadegh.j]

Re: Error in ADS

ya, I'll make a new post.

Appreciate your help man.