clear all;
close all;
N=20;

b=[1 -exp(j*2*pi*12/N)];
a=[1 -2*cos(2*pi*12/N) 1];
Hq = dfilt.df2(b, a);
Hq.arithmetic = 'fixed';
zplane(Hq,'off');

Above code is implementing discrete time direct form 2 filter.
After running code figure show pole zero plot of reference pole & zero and quantized 
pole & zero.
I want to know quantized level of pole and zero and how to control level of quantizing above implementation.