An Efficient Low Voltage Buck Regulator in 180nm

Abstract

A current sensing circuit which is fully integrated suitable for low voltage buck regulator is presented. The current sensing circuit presented operates with accuracy close to 100 percent. It is targeted to be fabricated with 180nm UMC technology. This IC senses faithfully till frequencies 2MHz and hence it works well for the buck converters whose switching frequencies are up to 2MHz. It is designed to operate with a biasing current of 100μA. The designed circuit is tested with a 1.8V buck converter and is found to sense the inductor current with an absolute error less than 1 percent against the LI-Ion battery voltage variation of 2.8 to 4.8V and a load current variation from 50mA to 200mA. The corresponding ripple is kept well below 20mV.