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

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

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

khouly

Hey dude!

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

Shot!

try to put the osciport in serise with the tank coil

if not work , try to increase the current

khouly

Funny stuff Khouly!

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

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

khouly

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?

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

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

What exactly you want?

Hey

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

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

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

we can ask some experts here :s

khouly

ya, I'll make a new post.

Appreciate your help man.

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