demodulation sin o square wave?

Hi,

i'd like to use AD8333 to demodulate a pass-band signal with 200kHz local oscillator.

The datasheet says that i can use both sin wave and square wave. My question is:

The use of a square wave produces spurious frequencies? It is better use Sin wave?

i need 200kHz very stable oscillator (low phase noise), i find one of GreenRay Industries, but the output is only square wave.

Is there a way to generate a 200kHz stable frequency sinusoidal?

thanks

Paolo