An efficient low voltage buck regulator in 180nm

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 180 nm UMC technology. This IC senses faithfully till frequencies 2 MHz and hence it works well for the buck converters whose switching frequencies are up to 2 MHz. It is designed to operate with a biasing current of 100 ??A. The designed circuit is tested with a 1.8 V 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 4.8 V and a load current variation from 50 mA to 200 mA. The corresponding ripple is kept well below 20 mV.