Low voltage techniques for bias circuits

Circuit design techniques for very low-voltage bias circuits are discussed. A Nagata current mirror is very suitable for battery operation because it provides current regulation. Also, it is very suitable for start-up circuitry. In this brief, an inverse Widlar current mirror is newly proposed as a nonlinear current mirror with a negative temperature coefficient (TC), a Nagata/inverse-Widlar current mirror is also proposed as a Nagata current mirror or an inverse-Widlar current mirror with an optionally programmed positive or negative TC, and a TC shifter with an offset voltage proportional to absolute temperature (PTAT) is also proposed. Furthermore, fundamental characteristics and temperature characteristics of the bias circuits discussed in this brief were verified with transistor-arrays and discrete components.