Analog VLSI implementations of continuous-time memory structures
The continuous-time implementation of the popular transversal filter is problematic since it is impossible to implement an ideal time delay in continuous-time hardware. We believe that building an ideal time delay would not be worthwhile anyway since the ideal time delay has shown to be inferior to low-pass (Gamma) and all-pass (Laguerre) stages in discrete-time simulations. We demonstrate feedforward analog VLSI implementations of the Gamma and Laguerre memory structures and show measurements of their performance. We also show through simulation of a system identification problem that the Laguerre filter is expected to converge faster and be more robust to the noise and offsets that we expect in an analog VLSI implementation.