Investigation of Low-Voltage, Sub-threshold Charge Pump with Parasitics Aware Design Methodology

This paper deals with cross-implementation of analytical and physical fundamentals of ultra low-voltage charge pumps. The analysis is based on precise, general formulas including characteristic parasitic effects valid for linear charge pumps. The parasitic effects are extended by non-linear parasitic capacitances represented as equivalent linear model of a switched transistor itself. The discussion about non-linear and linear behaviour of these parasitics is also included and demonstrated using cross-coupled, dynamic threshold implementation, where the EKV model of transistors has been utilized. The paper also introduced a new design rule for design of charge pumps based on transistors working in sub-threshold region to maximize the power throughput. This is achieved by tuning the operation conditions to the boundary case.