how to deal with "ac phase"

[liucheng311]

hi,deal all
i meet a problem when i simulate a multiplier with spectre,as we know,the formula of a multiplier is VOUT=k*v1*v2(v1 and v2 are the two terminals of the multiplier),i use vsin as the stimulation source to simulate the coefficient k.
the simulation result indicates that the VOUT is higher when i assign the ac phase of both vsins 0 than when i assign the ac phase of one vsin 0,the other 180. and i can not understand this.
could anyone help me explaining it?? and how should i deal with the parameter "ac phase" of the two vsin??

 

[chuckey]

When you multiply two sine waves, the resultant consists of a string of frequencies some of which are second harmonics of the input frequencies. Depending on the phase of the harmonics they can add or subtract from the fundamental at its peak, so it looks lower. Obviously the phase of the harmonics change at twice the rate of the fundamental frequencies.
Frank

 

[liucheng311]

thank you for you explaination,that is reasonable
so should i assign the two "ac phase"s 0 when i simulate it??