Is anyone can tell me the advantages of the capaciter connecting like this in the VCO cell?

I want to konw why it cennects between the  differential output?

Berti wrote on May 15^th, 2008, 12:07am:


Berti is correct -  Look at the equivlanet small signal circuit that is ground connected, it would be 2 capacitors from the two signal nodes to ground. Take the differential approach and the capacitor gets connected accross the signal nodes instead, and the total capacitance gets divided by two in value (insted of C1, C2 each being 1pf, the Cacross would be 0.5pf)

Add to that a differential system with no capactive load to ground noise.
Whenver possible, you want to keep systems differential.

-- Jerry