Method and apparatus for finite impulse response filter under constrained sampling rate

A constrained sampling rate filtering circuit, comprising:

• a first circuit configured to receive a first input signal and output an output signal with a first rate without aliasing the first input signal;
• a segmentation circuit configured to segment the output signal into a defined number of streams without aliasing, wherein each stream of the defined number of streams has an effective sample rate not greater than a second rate and the second rate is less than the first rate;
• a filter circuit configured to determine filter coefficients for a finite impulse response filter;
• the constrained sampling rate filtering circuit configured to group the filter coefficients into subsets of filter coefficients to match the defined number of streams;
• the constrained sampling rate filtering circuit configured to apply in parallel, for each stream of the defined number of streams, a subset of filter coefficients to a corresponding stream;
• a combiner circuit configured to combine at least some outputs from the defined number of streams into a combined result signal conditionally based on the second rate, wherein the combined result signal is mathematically equivalent to applying finite impulse response filtering to the output signal at the first rate;
• and
• the combiner circuit configured to output the combined result signal at a rate not greater than the second rate.

A system, comprising:

• a first circuit configured to receive an input signal and output an output signal with a first sample rate without aliasing the input signal;
• a second circuit configured to handle input signals up to a second sample rate, where the second sample rate is less than the first sample rate;
• and
• a third circuit configured to:
• process the output signal with the first sample rate from the first circuit by segmenting the output signal with the first sample rate into a defined number of streams, wherein each stream of the defined number of streams has an effective sample rate less than the second sample rate;
• apply finite impulse response filtering by processing the defined number of streams in parallel;
• combine at least some outputs of the defined number of streams into a combined result signal conditionally based on the second sample rate without aliasing, wherein the combined result signal is mathematically equivalent to applying finite impulse response filtering to the output signal at the first sample rate;
• and
• output the combined result signal to the second circuit at a rate not greater than the second sample rate.