Locally recurrent networks with multiple time-scales
We introduce a new generalized feedforward structure that provides for multiple time scales. The gamma, Laguerre and other locally recurrent feedforward structures perform poorly in cases where widely varying time constants are required. By exponentially varying the time-constant along the delay line, a single delay line is able to represent signals that include various time scales. We demonstrate both discrete- and continuous-time versions of this multiple time-scale structure which we call the multi-scale gamma filter. The multi-scale gamma has a very natural implementation in sub-threshold CMOS and measured impulse responses from a continuous-time analog VLSI chip are shown.