A Sparse-Input Multiplexer

Under one aspect, a method is provided for detecting events that are sparse in time. The method can include (a) receiving N analog input signals that are continuous and are independent from one another, wherein each one of the events causes a change in a corresponding one of the analog input signals, and N is 2 or greater. The method also can include (b) by a first analog circuit, for each of the N analog input signals, outputting products of that analog input signal and a plurality of gain factors. The method also can include (c) by a second analog circuit, outputting M sums of the products, wherein M is 2 or greater and is less than or equal to N. The method also can include (d) detecting a first one of the events based on the M sums of the products.