A Successive-Approximation Switched-Capacitor DC-DC Converter With Resolution of V-IN/2(N) for a Wide Range of Input and Output Voltages

作者：Bang Suyoung^*; Blaauw David; Sylvester Dennis

来源：IEEE Journal of Solid-State Circuits, 2016, 51(2): 543-556.

DOI：10.1109/JSSC.2015.2501985

• Fine-grained voltage generation
• fully integrated power converter
• on-chip voltage regulator
• power management unit
• successive-approximation (SAR) switched-capacitor (SC) converter
• SC DC-DC converter

A fully integrated successive-approximation (SAR) switched-capacitor (SC) DC-DC converter is presented that overcomes the coarse output voltage resolution limitation of traditional SC converters. An SAR SC converter cascades multiple stages of 2: 1 SC converters, and achieves a fine-grained conversion ratio resolution of V-IN/2(N), where V-IN is the input voltage and N is the number of stages. As the SAR SC converter generates the output voltage through SAR, each stage of 2: 1 SC converter provides a fixed voltage level, requiring minimal configuration change for regulation. Analysis shows that the SAR SC converter has a slow-switching-limit output impedance increasing proportionally to log(2) (number of resolution), and switching loss of bottom-plate parasitic capacitor decreasing with the number of stages. As a test chip, an SAR SC converter with 7 b resolution is fabricated in 180 nm CMOS process and implemented by cascading 4: 1 and five 2: 1 two-phase interleaving SC stages. It achieves 31.25 mV voltage resolution with output voltages over 0.4 V at V-IN = 4V. Using this fine grain voltage regulation approach, line and load regulations are implemented with a feedback/feedforward controller with peak efficiency of 72% for load currents from 0 to 300 mu A. The test chip occupies 1.69 mm(2) and utilizes on-chip capacitors of 2.24 nF in total.

• 出版日期2016-2