Issue in "spectrum" function of Cadence

 Hi All,

While calculating the SNR,ENOB using the "spectrum" function in calculator,I seem to be getting rather erroneous results. As seen in the attachment, I am getting "-1.9 bits" as my resolution and the SNR/SFDR is 0!!  I really don't understand this why.

I have followed the below steps for the above results

Sent the transient output data to calculator. This is my input signal to the spectrum function.

32768 is the number of bins I desire to use

800K is the bin size. My transient simulation time was 1.25u

1 is the starting FFT frquency

13.1072G is the end FFT frequency.  // I had also performed a dft of the same signal from which I obtained the input & output signal       frequencies.

Please let me know what is the problem. Is this an issue with Cadence or in the manner in which the computation is being done?

Thanks!

Kashif