Hello everyone. I am currently designing a low power consumption and low phase noise cross-coupled VCO in ADS. But I'm not getting the oscillating waveform when performing the transient response. Can anyone please help me with the issue. Thanks in advance.

 

Sure seems the collector supply at 1V too low ?


Regards, Dana.

 

Sure seems the collector supply at 1V too low ?


Regards, Dana.

Lower the voltage supply, lesser will be the power consumption.

 

C1 and C2 should connect to respective transistor bases, not to each other.
If the simulator is to be believed, you've created a -333 megaVolt generator .

 

C1 and C2 should connect to respective transistor bases, not to each other.
If the simulator is to be believed, you've created a -333 megaVolt generator .

Thankyou for your reply. May I know how do I make the circuit oscillate after connecting the capacitors to the base of the transistors.

 

I don't use ADS, but in the LTspice simulator you can specify a start-up condition, e.g. by giving one of the capacitors an initial voltage so that the circuit isn't completely symmetrical to start with.

 

I don't use ADS, but in the LTspice simulator you can specify a start-up condition, e.g. by giving one of the capacitors an initial voltage so that the circuit isn't completely symmetrical to start with.

Ok.thanks.

 

Lower the voltage supply, lesser will be the power consumption.

I understand that. But at 1V do you have enough reverse bias on collectors
to get transistors to function as transistors, especially on c old side of operation ?


Regards, Dana.

 

I understand that. But at 1V do you have enough reverse bias on collectors
to get transistors to function as transistors, especially on c old side of operation ?


Regards, Dana.

Thanks for your reply. May I know how much supply voltage would you recommend to function the transistors properly?

 

Something missing from your circuit, once you have the caps connected properly, is a respective pull-up resistor from each base to the +ve supply rail.

 

Depends on part.

This shows at low Vce you are close to saturation, and given your Vbe is relatively
fixed this tells you what Vcb should be doing. You don't want clipping if you are trying
to amp a signal. This also effects dynamic range of signal swing at collector.




Regards, Dana.

 

There is no generation inductance with your value. I suppose that a low value of quality.
See