A Sense-FET-Based Charge Sensor With Auto-Zero Offset Cancellation and 3.1 ns Response Time for Charge Control of SIMO DC-DC Converters

IEEE International Conference on Electronics, Circuits and Systems (ICECS), pp. 1–4

Abstract

This work presents a charge sensor circuit targeting low cross-regulation charge control of SIMO DC-DC converters. It uses a sense-FET-based current sensor, combining auto-zeroing for offset cancellation with a high-bandwidth BiCMOS implementation that effectively reduces the bandwidth and phase margin variation across the input current range. Implemented in 180 nm BCD-on-SOI, it achieves a fast response time of 3.1 ns, while supporting a wide input current range from -0.4 A to 1.5 A by superimposing an offset current into the sense-FET. The impact of the auto-zero offset cancellation on the charge sensor accuracy is investigated in the specific context of charge-controlled SIMO converters and the implication on the cross-regulation performance. A substantial reduction of the charge sensing error from +10/-12.5% to +1.9/-0.8% is demonstrated as a result of the proposed auto-zeroing.

Authors 4

1. Erik Wehr Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Integrated Analog Circuits and RF Systems,Aachen,Germany,D-52074

2. Kenny Vohl Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Integrated Analog Circuits and RF Systems,Aachen,Germany,D-52074

3. Ralf Wunderlich Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Integrated Analog Circuits and RF Systems,Aachen,Germany,D-52074

4. Stefan J. Heinen Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Integrated Analog Circuits and RF Systems,Aachen,Germany,D-52074