FREQUENCY TO VOLTAGECONVERTERByPrashant singhimi2011003
TABLE OF CONTENT1.Introduction.2.Basic FVC.3.Proposed FVC.4.Block Diagram.5.Hardware description.6.Advantage.7.Disadvantage.8.Conclusion.
INTRODUCTION Electronic devices that generate an output voltageor current proportional to the frequency ofsinusoidal input signal. It include op-amp for signal processing and RCnetwork for removing frequency-dependentripples.
BASIC FVC This is realized by a differentiator, an integrator, adivider and a square-rooter.A 1-4 GHz Frequency-to-Voltage Converter Design Department of Electronics Engineering, National Chiao -TungUniversity, 1001 University Road, Hsinchu, Taiwan
CONT.. The division of the differentiator output to theintegrator output causes large spikes when aninitial value of the integrator is not zero. Here output is proportional to input frequencywithout the influence of the input power.
PROPOSED FREQUENCY TO VOLTAGECONVERTER It is composed of a differentiator, two RMS-DCconverters, and a divider. Both include a frequency discrimination path andinput power calibration paths. In the frequency discrimination path, the inputfrequency was discriminated by an integrator ordifferentiator, respectively.
CONT… The RMS-DC converter is used to detect theoutput amplitude of the integrator or differentiator. In the input power calibration paths, which areonly composed of a RMS-DC converter for inputpower level detection. Finally, the current or voltage dividers are used toacquire the value of the input frequency.
Frequency discrimination path contains anintegrator or differentiator and RMS-DC converter. the input frequency is discriminated by anintegrator or differentiator Output amplitude of the integrator or differentiatoris discriminated by RMS-DC converter. Input power calibration path detects input powerlevel .
Current or voltage dividers are used to get thevalue of the input frequency. Frequency discrimination converts the signal to aDC voltage Vf by power detection. Composed of an attenuator and another powerdetector, the input power calibration path gives aDC voltage (Vcal) as a reference to calibrate thesignal amplitude
CONT.. The input signal is a pure sinusoidal signal with apeak amplitude of A and input frequency of ωn.
The derivative of this signal at the output of thedifferentiator will be -where τd is the time constant of the differentiator. Feeding Vin(t) and Vd(t) into the RMS-DCconverters yields the results as-
Dividing (4) by (3) we get- where k=kdiv τd is the sensitivity of the converterand kdiv is the scaling factor (gain) of the divider. The output signal is linearly proportional to theinput frequency, ωn , and insensitive to the inputsignal amplitude, A.
BLOCK DIGRAM CONT..Simple and Accurate Frequency to Voltage Converter A. Lorsawatsiri1, W. Kiranon1, V. Silaruam2, W. Sangpisit1, and P. Wardkein1 1 Faculty ofEngineering, King Mongkut’s Institute of Technology Ladkrabang Ladkrabang, Bangkok 10520, THAILAND
HARDWARE DESCRIPTION 5 operational amplifiers and 3 analog multipliersare used. One of the op-amp is used for performing thedifferentiator. The time constant of the differentiator,τd can be setby adjusting the resistor, R1 , and/or the capacitor,C1 , values. Other operational amplifiers are connected withmultipliers to realize RMS-DC converters
CONT.. The last multiplier is used as a divider. The Vg voltage is employed for adjusting thescaling factor, kdiv , of the divider. Input signal, Vin(t ), is sent to two paths. One is fed to the differentiator and then sent to theRMS-DC converter I.
CONT.. Other is fed to the RMS-DC converter II. Next, those outputs are sent to the divider tomanipulate a DC voltage that represents thefrequency of sinusoidal input signal as the outputof the FVC.
ADVANTAGE- A multi-GHz frequency-to-voltage converter isdesigned and implemented with this module. Input power calibration is possible in proposedmodel..
DISADVANTAGE- Less accurate. Non-linear due to integrator.
APPLICATION Power control. Communication. Instrumentation system. Measurement system .
CONCLUSION With proposed method , spikes effect are solved. Additionally the operating frequency has beenraised to 1 GHz to 4 GHz.