A low-voltage, low quiescent current, low drop-out regulator

Abstract

The demand for low-voltage, low drop-out (LDO) regulators is increasing because of the growing demand for portable electronics, i.e., cellular phones, pagers, laptops, etc. LDO's are used coherently with dc-dc converters as well as standalone parts. In power supply systems, they are typically cascaded onto switching regulators to suppress noise and provide a low noise output. The need for low voltage is innate to portable low power devices and corroborated by lower breakdown voltages resulting from reductions in feature size. Low quiescent current in a battery-operated system is an intrinsic performance parameter because it partially determines battery life. This paper discusses some techniques that enable the practical realizations of low quiescent current LDO's at low voltages and in existing technologies. The proposed circuit exploits the frequency response dependence on load-current to minimize quiescent current flow. Moreover, the output current capabilities of MOS power transistors are enhanced and drop-out voltages are decreased for a given device size. Other applications, like dc-dc converters, can also reap the benefits of these enhanced MOS devices. An LDO prototype incorporating the aforementioned techniques was fabricated. The circuit was operable down to input voltages of 1 V with a zeroload quiescent current flow of 23 A. Moreover, the regulator provided 18 and 50 mA of output current at input voltages of 1 and 1.2 V, respectively.

Distributed LDO regulators in a 28 nm power delivery system

“…While the impedance-attenuated-buffer in [11] is dynamically biased, the error amplifier in [11] is statically biased, making simultaneous optimization of the LDO speed and current consumption difficult. Alternatively, adaptive biasing techniques have been proposed that boost the bias current during fast output transitions [12,13,18], yielding a promising technique for fast and power efficient load regulation. The LDO in [13], however, utilizes a 1 lF off-chip capacitor to stabilize the voltage regulation, significantly increasing the response time of the regulation loop.…”

“…To achieve a fast transient response for a load current step of hundreds of microamperes, the quiescent current of an LDO is typically increased [8,18], lowering the current efficiency. Dynamically biased shunt feedback, proposed in [11], has been applied to achieve high current efficiency and system stability over a wide range of load currents.…”

Laplace transform-based theoretical foundations and experimental validation: low-frequency supercapacitor circulation for efficiency improvements in linear regulators

“…In commercial systems, this technique is called the point of load (POL) supply [25]. LDOs operate in the same manner as standard NPN regulators apart from the pass transistor being replaced by a single PNP or a PMOS transistor which can hold its output voltage in regulation with much lower voltage differences across the series element [16][17][18]26].…”

“…In the power conversion area, dominated by switching power supply based DC-DC converter techniques, low dropout regulators (LDO) were introduced to address the requirements of noise-sensitive and fast transient loads in portable devices [16][17][18][19][20][21][22][23][24]. In an LDO where V in is the unregulated input voltage and V out is the regulated output voltage, if the control circuits consume minimal power compared to the output power, the approximate efficiency is given by,…”

An unconditionally stable Voltage Regulator

“…Additionally it provides more noise at the regulated output due to its switched operation [3]. The low-dropout (LDO) voltage regulators is one of the most popular power converters used in power management [4] and is more suitable for an implanted system. The pass element can be implemented using bipolar or MOS transistors.…”