FREQUENCY TO VOLTAGE CONVERTER

By Prashant singhimi2011003

TABLE OF CONTENT

1.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 voltage or current proportional to the frequency of sinusoidal input signal.

It include op-amp for signal processing and RC network for removing frequency-dependent ripples.

BASIC FVC This is realized by a differentiator, an integrator, a

divider and a square-rooter.

A 1-4 GHz Frequency-to-Voltage Converter Design Department of Electronics Engineering, National Chiao -Tung University, 1001 University Road, Hsinchu, Taiwan

CONT..

The division of the differentiator output to the integrator output causes large spikes when an initial value of the integrator is not zero.

Here output is proportional to input frequency without the influence of the input power.

PROPOSED FREQUENCY TO VOLTAGE CONVERTER

It is composed of a differentiator, two RMS-DC converters, and a divider.

Both include a frequency discrimination path and input power calibration paths.

In the frequency discrimination path, the input frequency was discriminated by an integrator or differentiator, respectively.

CONT…

The RMS-DC converter is used to detect the output amplitude of the integrator or differentiator.

In the input power calibration paths, which are only composed of a RMS-DC converter for input power level detection.

Finally, the current or voltage dividers are used to acquire the value of the input frequency.

Basic Block Diagram

Detailed Structure

Proposed block diagram[2]

Frequency discrimination path contains an integrator or differentiator and RMS-DC converter.

the input frequency is discriminated by an integrator or differentiator

Output amplitude of the integrator or differentiator is discriminated by RMS-DC converter.

Input power calibration path detects input power level .

Current or voltage dividers are used to get the value of the input frequency.

Frequency discrimination converts the signal to a DC voltage Vf by power detection.

Composed of an attenuator and another power detector, the input power calibration path gives a DC voltage (Vcal) as a reference to calibrate the signal amplitude

CONT..

The input signal is a pure sinusoidal signal with a peak amplitude of A and input frequency of ωn.

The derivative of this signal at the output of the differentiator will be -

where τd is the time constant of the differentiator. Feeding Vin(t) and Vd(t) into the RMS-DC

converters yields the results as-

Dividing (4) by (3) we get-

where k=kdiv τd is the sensitivity of the converter and kdiv is the scaling factor (gain) of the divider.

The output signal is linearly proportional to the input frequency, ωn , and insensitive to the input signal 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 of Engineering, King Mongkut’s Institute of Technology Ladkrabang Ladkrabang, Bangkok 10520, THAILAND

HARDWARE DESCRIPTION 5 operational amplifiers and 3 analog multipliers

are used. One of the op-amp is used for performing the

differentiator. The time constant of the differentiator,τd can be set

by adjusting the resistor, R1 , and/or the capacitor, C1 , values.

Other operational amplifiers are connected with multipliers to realize RMS-DC converters

CONT..

The last multiplier is used as a divider. The Vg voltage is employed for adjusting the

scaling factor, kdiv , of the divider. Input signal, Vin(t ), is sent to two paths. One is fed to the differentiator and then sent to the

RMS-DC converter I.

CONT..

Other is fed to the RMS-DC converter II. Next, those outputs are sent to the divider to

manipulate a DC voltage that represents the frequency of sinusoidal input signal as the output of the FVC.

ADVANTAGE-

A multi-GHz frequency-to-voltage converter is designed and implemented with this module.

Input power calibration is possible in proposed model.

.

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 been

raised to 1 GHz to 4 GHz.

REFERENCES

http://www.globalspec.com/learnmore/data_acquisition_signal_conditioning/signal_converting/frequency_to_voltage_converters

http://www.wisegeek.com/what-is-a-frequency-to-voltage-converter.htm

www.analog.com/static/imported files/data_sheets/AD734.pdf

THANK YOU