We propose a novel circuit for noise rejection, which is composed mainly of a linear amplifier, a nonlinear amplifier, and a filter. The input signal is applied to a linear amplifier, a bandpass limiter, and an envelope detector followed by a low-pass filter. The output of the lowpass filter is multiplied by the output of the bandpass limiter. The difference between the output of the multiplier and linear amplifier is the output of the proposed circuit. It is then indicated that the proposed circuit rejects noise, of which amplitude is narrow-band relative to the desired signal or noise phase.

The effect of an arbitrary power-series envelope detector on signal-to-noise ratio (SNR) for non-Gaussian noise is considered. It is found that the insertion of the region of saturation in the input-output characteristic of the power-law envelope detector results in the improvement on the output SNR when input SNR is large.

The effects of thenth law amplifier on signal-to-noise ratio has not been represented as a function of the input signal-to-noise ratio when the input of the nonlinear device contains nonGaussian noise. In this paper, we analyze these effects and determine the improvement factor represented by the ratio of the output SNR to the input SNR. The results are illustrated by the calculation of the improvement factor for the cases where the input noise amplitude distributions are the uniform distribution, the triangle distribution, and the Rician distribution.