An ultra low power current-mode filter for neuromorphic systems and biomedical signal processing

Current-mode log-domain CMOS filters have favorable properties, such as wide dynamic range at low supply voltage, compactness, linearity and low power consumption. These properties are becoming increasingly important for biomedical applications that require extremely low-power dissipation and neuromorphic circuits that attempt to reproduce the biophysics of biological neurons and synapses. We present a current-mode log-domain integrator circuit with tunable gain that is extremely compact, compared to analogous state-of-the-art solutions. We show how the circuit proposed can implement a wide range of cut-off frequencies, extending over four orders of magnitude and dissipates less than 1 nW for cutoff frequencies lower than 100 Hz.We derive the circuitpsilas linear and non-linear characteristics through analytical derivations, present SPICE simulations that are in accordance with the theoretical analysis, and show measurements from a test chip comprising the VLSI implementation of the circuit proposed.