As described above, the quantizer degrades the signal if its (peak-to-peak) amplitude is above an upper bound . The minimum change in signal amplitude that can be expressed is limited by the quantization step . Thus a given quantizer operates over a limited range of input voltage amplitude called its dynamic range. The Dynamic range of a quantizer is usually defined by the ratio of the power of a sinusoidal signal with peak-to-peak amplitude = to the variance of the quantization noise. For an ideal quantizer with uniform quantization the dynamic range is . Thus the dynamic range is larger if the number of bits used for quantization is larger.