Unclear point about quantization
Quantization is a process of representing real values of a signal using integer numbers. That process results in loss of accuracy, which is determined by the selection of the smallest value of quantization level.
If the smallest quantization level is $\Delta$, then every signal level will be rounded to the multiple of that $\Delta$. For example, if a signal level is $x=3,3 V$ and $\Delta = 1V$, then the corresponding quantized representation of the signal level will be $Q(x)=3\Delta$ and the resulting $\hat x = 3_{10} = 11_2$. If $\Delta = 0.5V$, then the signal level will be $Q(x)=7\Delta$ and the resulting $\hat x = 7_{10} = 111_2$.
So, to rephrase the original point: the weight of the least significant bit of the binary code word equals $\Delta$.