A Novel Current Feed-back Sub-Nano-Siemen Transconductance Circuit Suitable for Large Time-Constant Bio-medical Applications

摘要

A novel (1/R - 1/g{sub}m - g{sub}m) circuit using current feedback technique capable of delivering sub-nano-siemen and lower transconductance values is proposed. Compared to most other nano transconductors which usually operate in weak inversion this circuit operates in the strong inversion saturation region and hence has a much more predictable behavior. It is suitable for application in Several-Hz to Sub-Hz Gm-C filters requiring large time constants. It can also be used for potentiostat designs in bio-electrochemical detection systems which has speeds in the range of several Hz. The transconductor demonstrates high linearity (THD ≈ -78dB) and noise immunity. Also, the transconductor can be suitably internally compensated with a high phase margin in order to prevent oscillatory behavior due to layout inherent parasitic feedback paths in a large Gm-C filter implementation.