A delta modulation encoder consisting essentially of a slope limiter and a delta modulator is disclosed. The slope limiter comprises an integrator, a subtraction circuit for generating the difference signal between the input analog signal and the output of the integrator, and an amplitude-limited amplifier, having preset saturation levels, for amplifying the output of the subtraction circuit and for supplying the amplified output to the integrator. The delta modulator encodes the output of the slope limiter into a delta-modulation signal. Thus, the slope of the input signal to the delta modulator is limited by the slope limiter to a value below the maximum slope which the delta modulator can follow.