captive oscillator circuit

Hi Dharshan,

PSpice simulators usually don't like having capacitor connections made where there isn't a dc path to ground, or somewhere. In you circuit you have C2 connecting to C5 and at their common connection point there isn't a dc return. You really don't need C2 in this circuit because it is simply in series with C5, and their approximate combined capacitance is equal to C5. Capacitor C5 is critical in relation to the phase shift it provides in conjunction with R1. That may solve your irregular circuit message.

Note that you don't need to provide connection wires between the commons of the various components. Just use the ground symbol for the ground connection side of the component. Also, understand that is sometimes difficult to get an oscillator to start up in simulation. You may have to experiment with setting some initial conditions for the circuit. There are 3 analysis choices within the Transient Analysis window. Try each one and see if the circuit oscillates with one of them.

One last thing, the voltage gain of the circuit is just about 1 V/V. It made need to be something more to overcome losses around the loop and actually have a gain of 1 V/V, or slightly higher. Remember that is one of the criteria for an oscillator. 

Regards, Thomas

PA - Linear Applications Engineering