Voltage regulator

About: Voltage regulator is a research topic. Over the lifetime, 33536 publications have been published within this topic receiving 350859 citations.

Voltage regulator that operates in either PWM or PFM mode

Abstract: A switching voltage regulator achieves high efficiency by automatically switching between a pulse frequency modulation (PFM) mode and a pulse-width modulation (PWM) mode. Switching between the modes of voltage regulation is accomplished by monitoring the output voltage and the output current, wherein the regulator operates in PFM mode at small output currents and in PWM mode at moderate to large output currents. PFM mode maintains a constant output voltage by forcing the switching device to skip cycles when the output voltage exceeds its nominal value. In PWM mode, a PWM signal having a variable duty cycle controls the switching device. A constant output voltage is maintained by feedback circuitry which alters the duty cycle of the PWM signal according to fluctuations in the output voltage.

A 0.5-mW passive telemetry IC for biomedical applications

Abstract: A low-power, single-chip, one-channel, fully implantable microtransponder system for low-frequency biomedical sensor applications is described. The circuit is powered by an external RF source at 27/40 MHz. No battery is required. Wireless communication with external monitoring units is realized by absorption modulation. As the radiated power received by a small coil can be as low as a few milliwatts, the data acquisition/transmission system has been optimized for low power consumption. The system has been integrated in a 2-/spl mu/m 40-V BiCMOS technology. It includes a low-offset amplifier, a low-pass notch filter, an A/D converter, a voltage doubler/rectifier, as well as a low-power voltage regulator. The implemented switched-capacitor amplifier features 45-/spl mu/V offset and an integrated noise of 21 /spl mu/V for a bandwidth of 30 Hz while consuming less than 30 /spl mu/W power. The digitized sensor data are transmitted as low duty-cycle PPM-AM signals with a rate of 1 kBd. The entire system, including the 1.6-k/spl Omega/ bridge sensor, consumes only 520 /spl mu/W, which makes it well suited for long-term monitoring of biomedical signals.

Performance-temperature optimization by cooperatively varying the voltage and frequency of a circuit

Abstract: A system and method using thermal feedback to cooperatively vary a voltage and frequency of a circuit to control heating while maintaining synchronization. Preferably, on-chip thermal sensors are used for feedback. A system having features of the invention includes: a thermal sensor coupled to the circuit, the thermal sensor generating a temperature signal which is a function of a temperature associated with the functional unit; a temperature decoder having an input and an output, the input coupled to the thermal sensor for decoding the temperature signal; a comparator having one input coupled to the decoder for comparing a decoded temperature signal with a predetermined temperature threshold signal coupled to a second input, the comparator enabling a voltage/clock control signal as a function of the decoded temperature signal and the predetermined temperature threshold; an adjustable voltage regulator coupled to the voltage/clock control signal; and a clock selector coupled to the voltage/clock control signal; wherein the voltage regulator and the clock selector are adapted to cooperatively vary the voltage and the frequency of the circuit to a predetermined voltage-frequency pair, responsive to the voltage/clock control signal and switching factor means, coupled to the comparator, for varying the switching factor of the circuit, wherein the switching factor is the fraction of clock cycles that the circuit is dissipating power.

A control scheme in hybrid synchronous-stationary frame for PWM AC/DC converter under generalized unbalanced operating conditions

Abstract: This paper proposes a new control scheme of improved transient response for the pulsewidth-modulation ac/dc converter under generalized unbalanced operating conditions. The overall-bandwidth diminishing filter/functional block for extracting positive and negative sequence components has been avoided by employing dual current regulators in positive- and negative-rotating synchronous frames. The steady-state error due to 120-Hz ac signals has been reduced by employing a resonant-gain path in the current regulator. This paper also proposes simplified current-reference calculation scheme in the regulation of instantaneous active/reactive power. Compared to the previous works, the proposed control method has better transient response in compensation for generalized unbalanced operating conditions (unbalanced input supply and unbalanced input impedances) of wide range while still satisfying unity input power-factor correction and ripple-free dc-output-voltage regulation without adding any external hardware. The proposed control system has been analyzed and tuned based on the ac small signal perturbed model under unbalance. Simulation and experimental results confirm the proposed control method under severe unbalanced operating conditions.

Design considerations for 12-V/1.5-V, 50-A voltage regulator modules

Abstract: The paper presents design considerations for a 12-V/1.5-V, 50-A voltage regulator module (VRM) for the next generation of microprocessors. The module has stringent power-density and transient-response specifications, which are hard to meet with traditional design techniques. The proposed design solutions increase the VRM efficiency, as well as achieve the desired transient response with a minimum amount of the output capacitance.