Practical Reconstruction: The Zero-Order Hold

In practice reconstruction of a continuous-time signal from samples is normally performed using a device called a zero-order hold. The zero-order hold puts out a voltage proportional to the amplitude of the discrete-time signal and holds that value for the duration of the sampling interval. The result is a stair-step approximation to the signal. This lesson analyzes the distortions introduced by the zero-order hold. It also shows you how an anti-imaging filter can be used after the zero-order hold to reduce the distortion.