One application of all-pass systems is phase equalization. Such equalization is usually performed to reduce waveform distortion of a signal passed through a system. Well known methods for equalizer design are derived in the frequency domain. Here, we present an approach which is based on the time-domain synthesis. We start from waveform distortion defined as the maximum value of the correlation between the system's input and the corresponding output signal. If the input signal is a sine pulse sequence, this maximum is equal to the peak amplitude of response's envelope. Based on this idea, we present a method for the design of IIR low-pass and band-pass equalizers. Furthermore, we give the relationship between the used time-domain criterion and its frequency-domain counterpart