How to convert IIR filter transposed direct form || SOS to traditional transposed direct form ||?

I have created a high pass butterworth filter in FilterDesigner tool in MATLAB. now I want to convert its structure to transposed direct form || and then do model realization. Is there a way I can realize it as traditional transposed direct form, as it existed in older versions of fdatool like R2012, and not second-order sections?

Answer 1

[Chunru]

% Get the filter coefficients (replace a and b with butterworth filter)
b = [0.3 0.6 0.3];
a = [1 0 0.2];

% >R2011a: differet structure of filter implementations
hd = dfilt.df1(b,a);
hd = dfilt.df2(b,a);
hd = dfilt.df1t(b,a);
hd = dfilt.df2t(b,a);

In using 'filterDesigner', go to edit-> Convert to single section (from sos).

[fateme mirabbasi]

Actually I don't want to use it in a code. I want to quantize the model I created in filterDesigner. I have done some quantization in filterDesigner tool and now I wont to realize my model in Simulink and do the rest of the quantization there by accessing building blocks of the model like coefficients and product and accumulators. but what when I double click on the model it's not what I want to see. Matlab has realized my filter in second order sections and I don't know how to deal with it now! I am used to quantizing my filters with the traditional model as a whole not seperate parts!

this is what I get in MATLAB2017b:

this is what I used to get in MATLAB2012b:

[Chunru]

if you are using 'filterbuilder', there is a choice of datatype. You can then select fix point implementation, the filter design will give the coefficients as specified format. if you are using filterbuilder, then there is a button for filter arithmetic. I am wondering if this is what you want.

[fateme mirabbasi]

even in filterbuilder there are only Second-Stage-Section structures available. I need my model as a whole not SOS structures.

[Chunru]

In 'filterDesigner', go to edit-> Convert to single section

[fateme mirabbasi]

Thank you very much. I converted it to single section