PSS and PXF analysis of Boost converter operating in Pulse Frequency Modulation

Hi,

In the circuit below, the VerilogA Comparator block (no hidden states) along with the RS Flip Flop is generating the switching frequency required for the ideal switch and keeps the boost converter operation in boundary condition mode.

Since there is no explicit clock in my circuit, I considered this as an autonomous circuit and in PSS analysis, I gave the oscillator node+ as the signal "q" and oscillator node- as "gnd". The beat frequency was given from transient analysis (transient analysis worked fine).

As I had to do PXF analysis, I also gave PAC magnitude and frequency (same as beat frequency) to the voltage and current sources. (I need transfer function from input voltage source to the output  Vo/Vi and transfer function from input current source to the output  Vo/Iin).

But I got the following error:

Error found by spectre during periodic steady state analysis `pss'.
    ERROR (CMI-2208): `I41' is a periodic input signal, which is inconsistent with autonomous circuits. 

Can anyone please tell me how I can overcome this problem?

Thanks in advance.