Switching activity reduced coding for low-power digital signal processing circuitry

A method for reducing unnecessary switching in a subsequent digital circuit, the method comprising:

• outputting a current output signal to the subsequent digital circuit;
• receiving a next input signal;
• determining, based on anticipated behavior of the subsequent digital circuit, whether the next input signal may be relevant to a next output of the subsequent digital circuit;
• if the next input signal may be relevant to the next output of the subsequent digital circuit, outputting the next input signal to the subsequent digital circuit;
• and
• if the next input signal will not be relevant to the next output of the subsequent digital circuit, outputting the current output signal to the subsequent digital circuit.

A finite impulse response filter comprising:

• a plurality of taps, each having a respective multiplier circuit;
• and
• a precoder circuit providing a current coded signal to the plurality of respective multiplier circuits, the precoder circuit comprising:
• a logic circuit that receives a next input signal and forms a next coded signal in response to the next input signal, the logic circuit having a first output state when the next coded signal may be relevant to next outputs of the plurality of multiplier circuits, and the logic circuit having a second output state when the next coded signal will not be relevant to the next outputs of the plurality of multiplier circuits;
• and
• an output circuit coupled to the logic circuit, the output circuit outputting the next coded signal to the plurality of multiplier circuits in response to the logic circuit having the first output state, and the output circuit outputting the current coded signal to the plurality of multiplier circuits in response to the logic circuit having the second output state.