Iir filter device and filtering method thereof

An Infinite Impulse Response, IIR, filter device, comprising:

• a header data module, configured to receive a current input data value and to latch the current input data value by overwriting an earliest historical input data value, maintaining that the current input data value and two historical input data values are stored;
• a filtering module, configured to perform multi-stage filtering calculations, and comprising an intermediate data module and a calculation module;
• wherein
• the intermediate data module comprises a first location and a second location corresponding to each stage of filtering, and is configured to use the first location corresponding to each stage of filtering to store an output data value of that stage of filtering, and to exchange an address of the first location and an address of the second location;
• the calculation module is configured, based on determining that a current stage of filtering is triggered, to read the current input data value and two historical input data values from a specified location, to read data values from a first location and a second location corresponding to the current stage of filtering in the intermediate data module as two historical output data values, to store the two historical output data values into a tail data module as two historical input data values for a next stage of filtering, to obtain a current output data value after filtering, and to trigger the next stage of filtering;
• the tail data module, configured to store the two historical output data values read by the calculation module as two historical input data values, and upon completion of any stage of filtering, to store an output data value of that stage as a current input data value for the next stage of filtering;
• wherein, a specified location for a first stage of filtering is the header data module, and a specified location for another stage of filtering is the tail data module.