Abstract
The switching noise and conversion efficiency of step-up DC-DC converters need to be improved to meet increasing demand. The delta-sigma modulation (DSM) technique is typically used to improve the performance of buck converters; however, this control scheme is not directly applicable for boost converters. This paper presents a boost DC–DC converter using a continuous-time delta-sigma modulator (DSM) controller for battery-powered and noise-sensitive applications. The proposed converter can adjust a wide range of output voltages dynamically by clamping the maximum duty cycle of the DSM, thus enabling stable and robust transient responses of the converter. The switching harmonics in the converter output are reduced effectively by the noise shaping property of the modulator. Moreover, the converter does not suffer from instability of mode switching due to the use of a fixed third-order DSM. Fabricated in a 180 nm CMOS, the converter occupies an active area of 0.76 mm2. It produced an output voltage ranging from 2.5 V to 5.0 V at an input voltage of 2.0 V and achieved a peak conversion efficiency of 95.5%. The output voltage ripples were maintained under 25 mV for all load conditions. A low noise output spectrum with a first spurious peak located −91 dBc from the signal was achieved.
Highlights
Portable electronic devices are typically equipped with a rechargeable lithium-ion battery with an output voltage range from 4.2 V to 2.7 V [1]
Because the digitalized output bitstream of the delta-sigma modulator (DSM) is determined by the difference between the reference voltage of the compensator (V REF ) and output voltage of the converter (V OUT ), a duty condition exceeding DMAX may occur under dynamic output voltage scaling where V REF is significantly higher than V OUT
This paper presents a low-switching-noise boost converter that uses a DSM controller with converter
Summary
Portable electronic devices are typically equipped with a rechargeable lithium-ion battery with an output voltage range from 4.2 V to 2.7 V [1]. Replacing the conventional pulse-width modulation (PWM) controller with a DSM can reduce the output harmonics and electromagnetic interference and yield high efficiency This control scheme is directly applicable for boosting converters [6,13,14]; the most practical limitation on the step-up conversion is that the maximum duty ratio (DMAX ) of the DSM controller cannot be adjusted as in conventional PWM controllers [15]. The proposed converter produces a wide range of scalable output voltages third-order DSM controller. The boost converter achieves a low output switching noise by using a limiter, controller, and compensator; Section. 2 introduces proposed boost converter architecture; Section 3 describes the detailed circuit of the duty cycle limiter, DSM controller, and compensator; Section 4 provides the experimental results of
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