A Bondwire Inductor Based Flash ADC Assisted DC-DC Buck Converter

A flash ADC-assisted fast transient response DC-DC buck converter is proposed in this paper. The proposed inductor-based DC-DC converter operates in continuous conduction mode (CCM). The novelty in architecture includes replacing SAR ADC with Flash ADC which converts the transient overshoot/undershoot into corresponding binary code at a faster rate as compared to SAR ADC. Depending on the overshoot and undershoot set criteria, the current pump injects the current into the output node to charge /discharge the output node to minimize the overshoot/undershoot and settling time. In the proposed design, required inductance is achieved by using bond-wire inductance, which reduces the chip's active area, and off-chip components. ADS simulations are performed for estimation of inductor values using the QFN-64 package. The proposed DC-DC converter occupies an active area of 0.91mm
²
using TSMC 130 nm bulk CMOS process. Post layout simulation results show the peak efficiency of 84% at V
in
of 3.3 V, V
out
of 1.8 V with the load current I
L
of 500 mA. The measured overshoot/undershoot in simulation is 70/60 mV with 530/469 ns recovery time and 7 mV output ripple. This enables the designed converter to be used in applications like aerospace, satellite, as well as military applications, where compactness is required.