A Novel Current-feedback Nano-Siemen Transconductance Circuit Suitable for Large Time-constant Applications

A novel transconductance circuit using current feedback transimpedance technique capable of delivering 2-60 nano-siemen ( ap 10^-9A/V) 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 ap -78 dB) 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.