VoutVin

VoutVin, often written as Vout/Vin, is the voltage transfer ratio of a circuit, representing how the output voltage responds to a given input voltage. It is a dimensionless quantity and a primary figure of merit for amplifiers, converters, and signal-processing stages. In decibels, this ratio is expressed as 20 log10(Vout/Vin).

In linear, time-invariant systems within their operating range, Vout is proportional to Vin: Vout = G * Vin, where G is the gain or transfer gain. In circuit analysis, the transfer function H(s) describes the relation in the complex frequency domain: Vout(s)/Vin(s) = H(s).

Common examples: in a non-inverting op-amp stage, the closed-loop gain is 1 + Rf/R1, giving Vout/Vin = 1 + Rf/R1. In an inverting op-amp stage, Vout/Vin = -Rf/Rin. A simple resistive divider yields Vout = Vin * (R2/(R1+R2)).

Frequency response shapes VoutVin. RC networks create low-pass or high-pass transfer functions; active filters may produce band-pass, notch, or other responses. In such cases, VoutVin varies with frequency as H(jω).

Limitations and measurement: VoutVin is bounded by supply voltages and device nonlinearity; at large signals, saturation or clipping reduces the effective gain. Designers characterize VoutVin using Bode plots, time-domain step responses, and oscilloscope measurements.