VFC with pulsewidth-to-period ratio proportional to input voltage
F.N. Trofimenkoff, J.W. Haslett, A. E. Nordquist · IEEE Transactions on Instrumentation and Measurement · 1986
A voltage-to-frequency conversion circuit with a pulse-width-to-period ratio proportional to an input voltage and to first order independent of circuit component values is described. The circuit can be modified to provide gain and linearization features at the cost of making the conversion gain dependent on resistance ratios. Applications of the circuit include transducer output linearization, analog multiplication, analog square root extraction, capacitance-to-period conversion, as well as two-wire or fiber-optic data transmission.