A local-feedback transconductor with improved linearity for low-power application

A local-feedback transconductor is known as a linear transconductor. For low current operation, transistors operate in weak inversion, and the voltage-current characteristic is not expressed as square-law characteristic but expressed as an exponential function. Then, the linearity is deteriorated. In this paper, a new linear MOS transconductor based on local-feedback transconductor is presented. Resistor degeneration used generally is insufficient to improve the linearity. The proposed method employs MOS transistors operating in triode region. Unlike the resistor degeneration, improvement of linearity is effective for small current operation, and transconductance is less deteriorated for larger current. Moreover, higher output resistance is obtained. Simulation results show the validity of the proposed technique.