SNRoutdB

SNRoutdB, or SNR_out in decibels, is a metric used to quantify the quality of an output signal produced by a system, after it has passed through a device such as an amplifier, filter, receiver, or digital processor. It expresses the ratio, in decibels, of the power of the desired signal at the output to the power of undesired noise present in the same reference bandwidth.

SNR_out_dB is calculated as 10 times the base-10 logarithm of the ratio of output signal power to output noise power: SNR_out_dB = 10 log10(P_signal_out / P_noise_out). The output signal power is the average power of the intended signal component at the output; the output noise power is the average power of noise within the reference bandwidth. If distortion is substantial, the ratio should be interpreted with SNDR in mind.

In a linear model, SNR_out_dB relates to the input SNR and the device’s noise figure (NF) by NF_dB = SNR_in_dB − SNR_out_dB, or equivalently SNR_out_dB = SNR_in_dB − NF_dB. The bandwidth used for measuring power must be specified and kept consistent.

SNRoutdB is widely used in evaluating amplifiers, filters, receivers, analog-to-digital converters, wireless links, and audio systems. It informs design trade-offs, dynamic range, and link budgets. Limitations arise from nonlinearity, distortion, measurement bandwidth, and averaging time.