*VIth Sem. M.Tech(Q.I.P.), Dept. Of ECE, NMAMIT Nitte
**Asst. Prof., Dept. of ECE, NMAMIT Nitte
***Sr. Asst. Prof., Dept. of ECE, MITE, Moodbidri
Online published on 21 August, 2014.
Signal to Noise Ratio (SNR) measurement plays a crucial role in evaluating the error rate performance of communication systems and to infer whether original message can be extracted from received signal or not. Hence there is a need to measure SNR in an accurate and simple way. The Operational Transconductance Amplifier (OTA) based SNR meter does this task. A noisy signal with additive noise is generated using an OTA based adder which forms the input to the SNR analyser. OTA based band pass filter tuned to signal frequency acquires the signal from the received noisy signal and after subtraction of the acquired signal from the received signal total noise is obtained. The OTA based mean square estimators estimate the mean square values of signal and noise. OTA based logarithmic amplifiers convert mean square values of signal and noise into log of the mean square values. OTA based differential amplifier with a differential gain of 10 with the inputs as log amplifier for signal and noise outputs, produces at the output SNR in dB.
In this paper the OTA based blocks of SNR Meter like Adder, filter, subtractor, mean square estimator, log amplifier and difference amplifier are designed and these blocks are interconnected to design and simulate the SNR Meter. Oscad simulator (an open source alternative to OrCad) is used to simulate the SNR Meter. The present designed SNR Meter estimates SNR in dB within ±10% of the ideal value. Performance analysis is done by comparing the SNR in dB obtained with calculated values.
Band Pass Filter(BPF), Mean Square Estimator Noise (MSEN), Mean Square Estimator Signal(MSES), Operational Transconductance Amplifier (OTA), Signal to Noise Ratio (SNR)
