The design of integrated switching regulators is a complex task and many degrees of freedom have to be considered compared to a traditional discrete Switched Mode Power Supplies (SMPS), where the power devices are usually off the shelf components. Design of such regulators allows for a more tailored power stage sizing, aiming to optimize the tradeoff between area and efficiency for a given application. On the other hand, the usage of low voltage devices to increase the overall converter efficiency brings some challenges in terms of reliability. Understanding the limits of certain technology within a certain application (with given constraints) is not a straightforward task.This paper presents a novel design methodology based on pre-computed Lookup Tables (LUTs), used to extract devices parameters and characteristics with SPICE-like accuracy. These parameters are then plugged into analytical equations in order to calculate the converter’s performance. A genetic algorithm is then used in order to efficiently explore the design space and find the Pareto-Optimum for a given set of objectives. The methodology is applied to the design of a simple half-bridge integrated buck converter in a 28nm CMOS technology. The power stage and the last gate driver stage are part of the optimization. Simulation results highlight the effectiveness of the proposed design methodology

Multi-Level Hybrid Flying Capacitor (MLHFC) converters are emerging high energy density dc-dc converters. This paper presents an online feedback stability region detection and flying capacitor (FC) balancing technique for MLHFC converters. The feedback region detector monitors the FC voltage and the internal control signal of the FC control loop to detect the feedback region and adapt the controller accordingly. The proposed detector is control type independent and can be embedded e.g. in a digital Sliding Mode Controller (SMC). In this work, the feedback detection mechanism directly acts inside the controller to balance the FC voltage. The analyzed controller offers a wide range of possible applications, resulting in a very versatile controller for MLHFC converters. Simulation results highlight the effectiveness and robustness of the proposed control architecture.

This paper presents a fully monolithic 3-Level Hybrid Flying Capacitor (3LHFC) converter based on a 130 nm technology node. The design targets a 28V-to-3.3V, 2 A, step-down dc-dc converter. An analog phase-shift modulator keeps the flying capacitor under control, and a dedicated startup circuit brings the flying capacitor to its target value in cold-start conditions. Integration of the full power stage on chip operating at 1 MHz switching frequency results in high conversion efficiency and in the reduction of the external passive components. The presented 3LHFC converter has been validated in silicon. Experimental results are shown and compared with the current state of the art.

In this paper, a digital implementation of a unified sliding mode controller for DC-DC converters is presented. Although current information is used as a control variable, a pure voltage-mode implementation has been considered and the inductor current ripple is digitally reconstructed. The proposed universal control algorithm can be applied to different converter topologies and operating modes. In particular, experimental results are shown for a prototyping system of a Buck converter operating in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM), where only negligible transient effects are present when changing the operation mode. The presented measurements confirm that the proposed universal control algorithm is capable of achieving tight voltage regulation and excellent dynamic performance under different operating conditions. Additionally, a comparison to a state-of-the-art digital Proportional-Integral-Derivative (PID) controller illustrates the performance improvement of the proposed digital control scheme.

Interest is apparently growing in the four-switch noninverting Buck-Boost converter, which can be effectively used as a power supply for mobile devices. A typical application is a dynamic power supply for third-generation (3G) Wideband Code Division Multiple Access (WCDMA) Power Amplifiers (PA). While several control strategies based on the linear control theory have been proposed recently, there is still room for investigation of nonlinear control techniques. In this paper, a fixed-frequency nonlinear controller based on the sliding mode theory is presented and compared to a classical linear Proportional-Integral-Derivative (PID) implementation. The main differences from the design perspective and in terms of performance are then pointed out and commented. The main advantages of the proposed technique generally include an improvement of the dynamic performance and increased energy efficiency of the conversion. Simulation results are provided in order to evaluate and compare the different control strategies.

In this paper, we study the advantages offered by multi-gate fin FETs (FinFETs) over traditional bulk MOSFETs when low standby power circuit techniques are implemented. More precisely, we simulated various vehicle circuits, ranging from ring oscillators to mirror full adders, to investigate the effectiveness of back biasing and transistor-stacking in both FinFETs and bulk MOSFETs. The opportunity to separate the gates of FinFETs and to operate them independently has been systematically analyzed; mixed connected- and independent-gate circuits have also been evaluated. The study spans over the device, the layout, and the circuit level of abstraction and appropriate figures of merit are introduced to quantify the potential advantage of different schemes. Our results show that, thanks to a larger threshold voltage sensitivity to back biasing, the FinFET technology is able to offer a more favorable compromise between standby power consumption and dynamic performance and is well suited for implementing fast and energy-efficient adaptive back-biasing strategies.