Analog RF Cochleas in Space and Time: From 1-D Circuits to Multi-dimensional Filter Banks
Conference
Mandal, S, Edussooriya, CUS, Gayanath, B et al. (2026). Analog RF Cochleas in Space and Time: From 1-D Circuits to Multi-dimensional Filter Banks
. Moratuwa Engineering Research Conference Mercon, 1124-1129. 10.1109/MERCon71835.2026.11691362
Mandal, S, Edussooriya, CUS, Gayanath, B et al. (2026). Analog RF Cochleas in Space and Time: From 1-D Circuits to Multi-dimensional Filter Banks
. Moratuwa Engineering Research Conference Mercon, 1124-1129. 10.1109/MERCon71835.2026.11691362
The radio frequency (RF) cochlea, a biomimetic LCR transmission-line filter bank that performs O(N) broadband spectrum analysis, has been demonstrated in active CMOS and as passive microwave channelizers but has remained a one-dimensional (1-D) structure since its introduction two decades ago. We argue that the natural next step is to add a second dimension, and we explore three complementary aspects of this extension. First, we review existing 1-D RF cochlea architectures and present a 20-channel, 1 GHz constant-bandwidth passive channelizer as a representative implementation. Second, we analyze the two-dimensional (2-D) cochlear-duct geometry of Watts and Neely using finite-difference and Liouville-Green simulations: the second dimension introduces a cut-off mode whose interference with the traveling-wave mode produces an upper-skirt roll-off 1.6-1.7× steeper than the 1-D long-wave limit at identical lumped parameters, equivalent to adding 12-25 second-order sections per e-fold of best frequency without changing the longitudinal stage count. We show that this advantage transfers to RF essentially area-neutrally, by partitioning the existing fluid inductance into a transverse inductor mesh that is finally physical at GHz frequencies. Third, we generalize from this specific 2-D cochlea to abstract multidimensional cochleas using Ramamoorty-Bruton synthesis of stable continuous-time LCR networks, yielding a mixed st-zx domain filter bank suitable for wideband antenna-array beamforming.
