Abstract-This paper presents a low-dropout regulator (LDO) for portable applications with an impedance-attenuated buffer for driving the pass device. Dynamically-biased shunt feedback is proposed in the buffer to lower its output resistance such that the pole at the gate of the pass device is pushed to high frequencies without dissipating large quiescent current. By employing the current-buffer compensation, only a single pole is realized within the regulation loop unity-gain bandwidth and over 65 phase margin is achieved under the full range of the load current in the LDO. The LDO thus achieves stability without using any low-frequency zero. The maximum output-voltage variation can be minimized during load transients even if a small output capacitor is used.The
A fully integrated soft-start circuit for voltage regulators is presented in this brief. A soft-start strategy based on a linearly ramped-up reference is adopted to prevent massive inrush currents through the power device during the start-up phase of the regulator. The strategy is realized by a compact on-chip circuit, which requires no external components and has minimal transistor overhead, thereby minimizing the implementation area and cost of the overall regulator. The proposed soft-start circuit has been implemented in a 0.35-μm high-voltage complementary metal-oxide-semiconductor technology as part of a linear regulator controller for automotive applications. The proposed soft-start circuit occupies 0.026 mm 2 on silicon, which corresponds to about one fifteenth of the total area of the linear regulator controller.Index Terms-Linear regulator, low-dropout regulator (LDO), power management integrated circuits, soft start, switching regulator, voltage regulators.
Abstract-Bootstrapped switches are used in a variety of applications including DC-DC converters, pipelined analog-to-digital converters and high voltage switches and drivers. Current work on highly integrated power management applications often requires the ability to measure voltage quantities that exceed the supply voltage in magnitude. This is primarily due to a basic need to maximize efficiency by running the power management IC on as low supply voltage as possible, while still maintaining the ability to sample and measure quantities from the surroundings that could well exceed the battery voltage. In this paper, a new bootstrapped switch is presented. The switch enables the precise sampling of input signals well greater than the chip supply voltage with no static power consumption, and without activating on-chip parasitic body diodes. The bootstrapped switch, presented here, is designed to sample an input signal with a 0-5.5-V range at a supply voltage of 2.75 V. Measurement data shows functionality for a 0-6-V input signal range with a supply voltage as low as 1.2 V.
Bootstrapped switches are used in a variety of applications including DC-DC converters, pipelined analog-todigital converters and high voltage switches and drivers. Current work on highly integrated power management applications often requires the ability to measure voltage quantities that exceed the supply voltage in magnitude. This is primarily due to a basic need to maximize efficiency by running the power management IC on as low supply voltage as possible, while still maintaining the ability to sample and measure quantities from the surroundings that could well exceed the battery voltage. In this paper a new bootstrapped switch is presented. The switch enables the precise sampling of input signals well greater than the chip supply voltage with no static power consumption, and without activating on-chip parasitic body diodes. The bootstrapped switch, presented here, is designed to sample an input signal with a 0-5.5 V range at a supply voltage of 2.75 V. Measurement data shows functionality for a 0-6 V input signal range with a supply voltage as low as 1.2 V.
A level-shifting circuit with sub-nano-second propagation delay for high input voltage switched-mode power converters is presented. The proposed circuit uses isolated lowvoltage NMOS transistors and capacitive coupling to shift the control signal of the high-side power switch from a low-voltage logic domain (VLogic ~ 5V) up to a high-voltage power domain (VIN ~ 65V) with less than 115ps propagation delay. As a result, the non-overlap time inserted between the control signals of the high-side and low-side power switches can be minimized, leading to higher efficiency. Moreover, the control signal is shifted to the high-voltage power domain without reducing its voltage swing, which helps minimizing the on-resistance of the switch and further improves efficiency. The proposed circuit is fully integrated in a 0.18µm technology with no off-chip components. It occupies less than 0.75mm 2 and provides built-in protection for the low-voltage devices with no additional protection circuitry. Transistor level simulations demonstrate the circuit's functionality and performance.
A fully-integrated soft-start circuit for voltage regulators is presented in this brief. A soft-start strategy based on an extremum selector and a linearly ramped-up reference is developed to prevent any massive in-rush current through the power device during the start-up phase of the regulator. The strategy is realized by a compact on-chip circuit that requires no external components and has minimal transistor overhead, thereby minimizing the implementation area and the cost of the overall regulator. The linearly ramped-up reference is created through the use of nonlinear MOS capacitors available in a low-cost bulk CMOS technology. The proposed soft-start circuit has been implemented in a 0.35-μm bulk CMOS technology as part of a 50-mA linear regulator. The proposed circuit occupies 0.013 mm 2 on silicon, which corresponds to about 13% of the total area of the linear regulator. The soft-start circuit enables the output voltage of the regulator to be linearly ramped up to the steady state under different load currents and charging currents.
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