I experiment with the coefficient quantization in an IIR filter. I change some values like the passband ripple and also how many bits i want for the quantization method. In the first picture i have 1db passband ripple , 'round'and 7-bits as the quantization method:
In the second picture i have 1.3db as the passband ripple ,'round' and 6-bits as quantization method.
These are the PZP diagrams. I dont understand how i can extract useful information from the diagrams in order to say which design is better or to make comparisons between these 2 designs.How the Poles and Zeros affect my decision for what is better?
edit: the images becomes bigger and more visible when you copy the url and open or select view image. Also with the green is the quantized and with blue the un-quantized coefficients.
edit2:As Matt asks for magnitude frequency response I have add the extra information:
1db passband ripple , 'round'and 7-bits
1.3db as the passband ripple ,'round' and 6-bits
EDIT: After the answer from Matt i need to add more information:
I want to find a set of quantized coefficients that meet the specification with the minimum number of bits. My specification is an 8th-order IIR filter with the following transfer function magnitude response: \begin{align*} 0\,\mathrm{db} \pm 1.5 \,\mathrm{db} & \quad \text{for } \quad 0.2<|v|<0.3 \cr \lt −60\,\mathrm{db} & \quad\text{for } \quad |v|<0.14\text{ and } |v|>0.36 \end{align*}
I use this matlab function: $ [b,a]=ellip(n,Rp,Rs,Wp) , $
after some trials i found that (the filter is implemented using second-order sections) : $ [b,a]=ellip(4,1,60,2*[0.2,0.3]) $ and using 7-bit quantization i take the diagram above that i think verify the specification (if i make a mistake please correct me) ,
but if a use: $ [b,a]=ellip(4,1.3,60,2*[0.2,0.3]) $ and 6-bit quantization also i take a reasonable result. My concern is if my thought and procedure is correct or i have a mistake and i need to stick with 7-bits quantization?