a first variable capacitor coupled to {HEAD ~ the first DAC} and {TAIL ~ the first buffer}, the capacitance value of the first variable capacitor corresponding to the first control voltage; and 
a first variable capacitor coupled to { HEAD ~ the first DAC } and { TAIL ~ the first buffer } , the capacitance value of the first variable capacitor corresponding to the first control voltage ; and
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH