Low-power switched capacitor voltage reference

Low-power analog design represents a developing technological trend as it emerges from a rather limited range of applications to a much wider arena affecting mainstream market segments. It especially affects portable electronics with respect to battery life, performance, and physical size. Meanwhile, low-power analog design enables technologies such as sensor networks and RFID. Research opportunities abound to exploit the potential of low power analog design, apply low-power to established fields, and explore new applications. The goal of this effort is to design a low-power reference circuit that delivers an accurate reference with very minimal power consumption. The circuit and device level low-power design techniques are suitable for a wide range of applications. To meet this goal, switched capacitor bandgap architecture was chosen. It is the most suitable for developing a systematic, and groundup, low-power design approach. In addition, the low-power analog cell library developed would facilitate building a more complex low-power system. A low-power switched capacitor bandgap was designed, fabricated, and fully tested. The bandgap generates a stable 0.6-V reference voltage, in both the discrete-time and continuous-time domain. The system was thoroughly tested and individual building blocks were characterized. The reference voltage is temperature stable, with less than a 100 ppm/°C drift, over a --60 dB power supply rejection, and below a 1 [Mu]A total supply current (excluding optional track-and-hold). Besides using it as a voltage reference, potential applications are also described using derivatives of this switched capacitor bandgap, specifically supply supervisory and on-chip thermal regulation

Measurement-based quantum control of mechanical motion

Controlling a quantum system based on the observation of its dynamics is inevitably complicated by the backaction of the measurement process. Efficient measurements, however, maximize the amount of information gained per disturbance incurred. Real-time feedback then enables both canceling the measurement's backaction and controlling the evolution of the quantum state. While such measurement-based quantum control has been demonstrated in the clean settings of cavity and circuit quantum electrodynamics, its application to motional degrees of freedom has remained elusive. Here we show measurement-based quantum control of the motion of a millimetre-sized membrane resonator. An optomechanical transducer resolves the zero-point motion of the soft-clamped resonator in a fraction of its millisecond coherence time, with an overall measurement efficiency close to unity. We use this position record to feedback-cool a resonator mode to its quantum ground state (residual thermal occupation n = 0.29 +- 0.03), 9 dB below the quantum backaction limit of sideband cooling, and six orders of magnitude below the equilibrium occupation of its thermal environment. This realizes a long-standing goal in the field, and adds position and momentum to the degrees of freedom amenable to measurement-based quantum control, with potential applications in quantum information processing and gravitational wave detectors.Comment: New version with corrected detection efficiency as determined with a NIST-calibrated photodiode, added references and revised structure. Main conclusions are identical. 41 pages, 18 figure

Output power limitations and improvements in passively mode locked GaAs/AlGaAs quantum well lasers

We report a novel approach for increasing the output power in passively mode locked semiconductor lasers. Our approach uses epitaxial structures with an optical trap in the bottom cladding that enlarges the vertical mode size to scale the pulse saturation energy. With this approach we demonstrate a very high peak power of 9.8 W per facet, at a repetition rate of 6.8 GHz and with pulse duration of 0.71 ps. In particular, we compare two GaAs/AlGaAs epilayer designs, a double quantum well design operating at 830 nm and a single quantum well design operating at 795 nm, with vertical mode sizes of 0.5 and 0.75 μm, respectively. We show that a larger mode size not only shifts the mode locking regime of operation toward higher powers, but also produces other improvements with respect to two main failure mechanisms that limit the output power, catastrophic optical mirror damage and catastrophic optical saturable absorber damage. For the 830-nm material structure, we also investigate the effect of nonabsorbing mirrors on output power and mode locked operation of colliding pulse mode locked lasers

SiC Band Gap Voltage Reference for Space Applications

Electronics for space applications can experience wide temperature swings depending on orientation towards stars and duty cycle of propulsion systems. Energy on satellites primarily comes from radiological thermal generators and / or solar panels. This requires space electronic applications to be energy efficient and have high temperature tolerance. As a result, space electronic systems use high efficiency SMPS [switching mode power supplies]. Currently, there exists SiC [silicon carbide] based electronics that is state of the art for high temperature applications. Commercial manufacturers at this time produce SiC Power MOSFETs [Metal Oxide Semiconductor Field Effect Transistors], which are the switching element of the SMPS. Although many commercial silicon SMPS controller IC’s [Integrated Circuits] are available on the market at this time, there are no SiC SMPS controller IC’s. The scope of this research project was sponsored by NASA which required the design, fabrication, and testing of a single module SiC SMPS controller. A subcomponent of the SMPS design was a BGR [bandgap voltage reference] for the controller. This thesis will cover the theoretical basis of the BGR, the development methods and challenges in the design of a SiC BGR; utilizing a commercial SiC process as a major constraint in the designs. These constraints were partially tackled by using topologies and techniques from the early days of n channel MOSFET based electronics established in the1970’s. The basis of design was models provided by the owner of the process. The BGR was designed with Kuijk BGR topology. These devices are currently being produced in the microelectronics foundry facility since the simulation analysis results have provided promising theoretical data depicting a simulated temperature stability of 16.5 ppm /℃ from 25-160 ℃

Model of Switched-Capacitor Programmable Voltage Reference: Optimization for Ultra Low-Power Applications

This paper proposes an analytical model for the optimized design of a switched-capacitor programmable voltage reference (SC-PVREF). This PVREF topology guarantees a straightforward design, easy portability across different technology nodes, and does not require any special technology option. The developed model allows the study of the trade-offs and the a priori evaluation of the system performance. Circuit optimization is carried out with MATLAB and permits SC-PVREF to achieve current consumptions of tens of nanoampere, suitable for ultra low-power applications

Pulse Compression with Superluminal Group Velocity in 1-D Photonic Bandgap Coplanar Waveguide

International audienceWe report on the analysis and design of a Photonic BandGap coplanar waveguide (CPW) that jointly exhibits pulse compression and superluminal group velocity in the so-called anomalous dispersion region for a Gaussian modulated signal. The coupling of an analytical analysis method with an optimization algorithm enables the design of a coplanar PBG to reach the specified function. Measurements confirm our simulation data and the relevance of our approach. Further to these experiments, a discussion on superluminal velocity fundamentals is proposed