A Low-Voltage Low-Power Comparator With Current-Controlled Dynamically-Biased Preampl
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01-11-2010, 12:14 PM
A Low-Voltage Low-Power Comparator With
Preamplifiers For DCM Buck Regulators
Department of Electrical Engineering,
The University of Texas at Dallas,
Richardson, TX 75080-3021, USA.
Comparator-controlled power switch has been widely used to improve power efficiencies of discontinuous-conductionmode (DCM) buck regulators. Some major design challenges are capabilities of the comparator to operate at low voltage and dissipate low power for low-voltage DCM buck regulators having high power efficiencies under light-load condition. This paper presents a new comparator with current-controlled dynamicallybiased preamplifiers. Current-controlled dynamic biasing (CCDB) is developed to lower the required supply voltage for realizing the autozeroing technique in the preamplifier, thereby allowing the proposed comparator to operate at lower supply voltage compared to that using conventional preamplifiers. The proposed CCDB technique also minimizes the current consumption of the comparator under different input amplitudes. Implemented in a standard 0.35-μm CMOS process with Vthn ≈ |Vthp| = 0.7 V, the comparator can operate down to 1.2 V and achieve 8-bit resolution at 20 MS/s while only consuming 7-μA current.
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