• Quantization is a process that converts sampled signal into an approximate quantized signal which consists of only a finite number of predecided voltage levels.

• It is a process of rounding off or approximation.

• Each sampled value at the input of the quantizer is approximated or rounded off to the nearest standard predecided voltage level.

• These standard levels are known as “quantization level”

• The quantization process takes place as follows:

• The input signal x (t) is assumed to have a peak to peak swing of $V_L$ to $V_H$ volts. This entire voltage range has been divided into “Q” equal intervals each of size “s”

• “s” is called as the step size and its value is given as,

• In the fig, the value of Q =8

• $q_0, q_1……. q_7$ are the quantization levels also called as decision threshold.

-$ x_q$(t) represents the quantized version of x (t).We obtain $x_q$(t) at the output of the quantizer When x(t) is in the range $∆_0$ then corresponding to any value of x(t) the quantizer output will be equal to “$q_0$”. Similarly for all the values of x (t) in the range ∆1 quantizer output will be equal to “$q_1$”

• Thus in each range from $∆_1$ to $∆_7$ the signal x(t) is rounded off to the nearest quantization level and the quantized signal is produced.

• The quantized signal $x_q$(t) is thus an approximation of x (t).

• The difference between them is called as quantization error or quantization noise.

• This error should be as small as possible.

• To minimize the quantization error step size “s” should be small as possible which is done by increasing the number of quantization level Q.