The frequency reference input is selectively at one of {HEAD ~ a first or second fixed voltage level} designating {TAIL ~ a first or second oscillator frequency}, and a variable signal level designating a frequency between the first and second oscillator frequencies 
The frequency reference input is selectively at one of { HEAD ~ a first or second fixed voltage level } designating { TAIL ~ a first or second oscillator frequency } , and a variable signal level designating a frequency between the first and second oscillator frequencies
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH