A 4-Phase DAB Current-Mode Hysteretic Controlled Buck Converter With Relaxed Inductor Requirements and Enhanced DC and Dynamic Performance

This article presents a four-phase current-mode hysteretic-controlled DC-DC buck converter with fixed-frequency double-adaptive-bound (DAB) control. In prior current-mode converter designs, there exists undesired output DC error caused by control loop delays and mismatches between the RC current sensing network and the DC resistance (DCR) of the power inductor. Circuit delay is also an obstacle in achieving higher switching frequency and multi-phase operation. To address these issues, ratioed sensing RC network and digital output DC calibration are proposed. To reduce the efficiency degradation caused by imbalanced phase current, digital current balancing (CB) calibration is also developed. To maintain a high efficiency with a wide output load range, digital active-phase-count (APC) function was also introduced, with burst mode (BM) to improve transient responses at fast load current steps. The proposed converter has been fabricated in 180-nm CMOS process and measured at 10 and 25 MHz with 18-to-100-nH miniature 0402 inductors, converting 1.8-V supply (V $_{\rm IN}$ ) to 0.6-1.5-V output with 93.9% peak efficiency.