Simulating pierce crystal oscillator

Thread Starter

Faiz Valensi

Joined Jun 16, 2014
7
Im simulating a pierce crystal oscillator on synopsys software. The design that i've made is to achieve 10MHz frequency. The problem is the circuit that ive made doesnt oscillate. Initial condition also been included before the inverter. Is there any error that I've made in this circuit? Thank you


RF = 1M Ohm
R1 = 1k Ohm
C0 = 6p F
Cstray = 5p F
C1 = C2 = 22p F
Pmos W/L = 6u/1u
Nmos W/L = 3u/1u
 

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SLK001

Joined Nov 29, 2011
1,543
Have you ever had an oscillator work in your simulator before? I ask, because an oscillator is fairly difficult to get to start in a simulator. What I do, is place a CLOSING SWITCH that closes at T=0.1 seconds in the base of the active element. Sometimes it works, sometimes it doesn't. Sometimes, changing the switch close time helps.

Also, your circuit isn't easily readable.
 

ScottWang

Joined Aug 23, 2012
6,860
When you asked for help, but you attached a unreadable value, I'm not sure how our helper how to help you?

Please reattach a clear circuit.
 

Thread Starter

Faiz Valensi

Joined Jun 16, 2014
7
Have you ever had an oscillator work in your simulator before? I ask, because an oscillator is fairly difficult to get to start in a simulator. What I do, is place a CLOSING SWITCH that closes at T=0.1 seconds in the base of the active element. Sometimes it works, sometimes it doesn't. Sometimes, changing the switch close time helps.

Also, your circuit isn't easily readable.
Im working with ring oscillator and also VCO circuit. And it works pretty well, only the pierce crystal oscillator doesnt oscillate
 

eetech00

Joined Jun 8, 2013
1,780
Hi

Where are you setting initial conditions? I don't see the setting(s) anywhere.
Try setting one side of the inverter (try output side) to 0 volts.
 

Thread Starter

Faiz Valensi

Joined Jun 16, 2014
7
Hi

Where are you setting initial conditions? I don't see the setting(s) anywhere.
Try setting one side of the inverter (try output side) to 0 volts.
Hello there.

I already set the initial condition at the input side (to 0 volt).
By the way is there any difference if i set the initial condition at the output side?
 

eetech00

Joined Jun 8, 2013
1,780
I would follow the rise of the power supply voltage.
Which side of the inverter reaches steady state first based on power up?
Are you able to set the ramp up time of all power sources?
Try setting the power supply voltage source rise time to 25uS.
Are you using the .UIC directive?

I mainly use LTspice and this is usually solved by ramping the power supply or
setting the initial conditions of specific nodes or devices (like caps).
 
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