Abstract: In order to solve the problems of high performance requirements and complex hardware circuits in
existing AC ( Alternating Current) voltage amplitude measurement methods． A voltage /frequency converter is
used to modulate AC voltage amplitude information into a digital frequency signal． By analyzing the digital
frequency signal，the AC voltage amplitude before modulation can be calculated． The mathematical relationship
between the output frequency of the voltage-frequency converter and the input AC voltage amplitude during the
conversion period is deduced in detail． An AC voltage amplitude detection circuit is designed which contains only
a voltage /frequency converter chip and a double operational amplifier． The experiment results show that the
method is correct and the circuit design is reasonable and effective． The method utilizes the easy integration
characteristics of digital frequency signals，and each test value is used to calculate the amplitude of the signal to
be measured． The simple circuit design reduces the design cost and improves the measurement stability．

Key words: voltage-to-frequency conversion, analog-digital conversion, integration