A Charge Pump Architecture with High Power-Efficiency and Low Output Ripple Noise in 0.5 μm CMOS Process Technology

The demand of portable consumer electronic devices is skyrocketing day-by-day. Such modern integrated microsystems have several functional blocks which require different voltages to operate adequately. DC-DC converter circuits are used to generate different voltage domains for different functional blocks on large integrated microsystems from a single voltage battery-operated power supply. Charge pump is an inductorless DC-DC converter which generates higher positive voltage or lower voltage or negative voltage from the applied reference voltage. A charge pump circuit uses switches for charge transfer action and capacitors for charge storage. The thesis presents a high power-efficiency charge pump architecture with low output ripple noise in the AMI N-well 0.5 µm CMOS process technology. The switching action of the proposed charge pump architecture is controlled by a dual phase non-overlapping clock system. In order to achieve high power-efficiency, the power losses due to the leakage currents, the finite switch resistance and the imperfect charge transfer between the capacitors are taken into consideration and are minimized by proper switching of the charge transfer switches and by using different auxiliary circuits. To achieve low output ripple noise, the continuous current pumping method is proposed and implemented in the charge pump architecture. The proposed charge pump can operate over the wide input voltage range varying from 3 V to 7 V with the power conversion efficiency of 90%. The loading current drive capability of the proposed charge pump is ranging from 0 to 45 mA. The worst case output ripple voltage is less than 25 mV. To prove the concept, the design of the proposed charge pump is simulated rigorously over different process, temperature and voltage corners

Circuit Modules for CMOS High-Power Short Pulse Generators

High-power short electrical pulses are important for high-performance functionality integration, such as the development of microelectromechanical/nanoelectromechanical systems (MEMS/NEMS), system on chip (SoC) and lab on chip (LoC). Many of these applications need high-power (low impedance load) short electrical pulses, in addition to CMOS digital intelligence. Therefore, it is of great interest to develop new circuit techniques to generate high-power high-voltage short electrical pulses on-chip. Results on pulse forming line (PFL) based CMOS pulse generator studies are reported. Through simulations, the effects of PFL length, switch speed and switch resistance on the output pulses are clarified. CMOS pulse generators are modeled and analyzed with on-chip transmission lines (TLs) as PFLs and CMOS transistors as switches. In the 0.13 um CMOS process with a 500 um long PFL, post layout simulations show that pulses of 10.4 ps width can be obtained. High-voltage and high-power outputs can be generated with other pulsed power circuits, such as Blumlein PFLs with stacked MOSFET switches. Thus, the PFL circuit significantly extends short and high-power pulse generation capabilities of CMOS technologies. A CMOS circuit with a 4 mm long PFL is implemented in the commercial 0.13 um technology. Pulses of ~ 160 ps duration and 110-200 mV amplitude on a 50 Ohms load are obtained when the power supply is tuned from 1.2 V to 2.0 V. Measurement Instruments limitations are probably the main reasons for the discrepancies among measurement and simulation results. A four-stage charge pump is presented as high voltage bias of the Blumlein PFLs pulse generator. Since Schottky diode has low forward drop voltage (~ 0.3V), using it as charge transfer cell can have high charge pumping gain and avoid additional control circuit for switch. A four-stage charge pump with Schottky diode as charge transfer cell is implemented in a commercial 0.13 um technology. Charge pump output and efficiency under different power supply voltages, load currents and clock frequencies are measured and presented. The maximum output voltage is ~ 6 V and the maximum efficiency is ~ 50%

A robust high-efficiency cross-coupled charge pump circuit without blocking transistors

This document is the Accepted Manuscript version of the following article: Minglin Ma, Xinglong Cai, Yichuang Sun, and Nike George, ‘A robust high-efficiency cross-coupled charge pump circuit without blocking transistors’, Analog Integrated Circuits and Signal Processing, Vol. 95 (3): 395-401, June 2018. Under embargo until 16 March 2019. The final publication is available at Springer via: https://doi.org/10.1007/s10470-018-1149-xA fully integrated cross-coupled charge pump circuit with a new clock scheme has been presented in this paper. The new clock scheme ensures that all NMOS pre-charge transistors are turned off when the voltages of main clock signals are high. Notably, all PMOS transfer transistors will be turned off when the voltages of the main clock signals are low. As a result, the charge pump eliminates all of the reversion power loss and reduces the ripple voltage. The proposed charge pump has a better performance even in scenarios where the main clock signals are mismatched. The proposed charge pump circuit was simulated using spectre in the TSMC 0.18 µm CMOS process. The simulation results show that the proposed charge pump circuit has a high voltage conversion efficiency and low ripple voltage.Peer reviewe

Heat, molecular vibrations, and adiabatic driving in non-equilibrium transport through interacting quantum dots

In this article we review aspects of charge and heat transport in interacting quantum dots and molecular junctions under stationary and time-dependent non-equilibrium conditions due to finite electrical and thermal bias. In particular, we discuss how a discrete level spectrum can be beneficial for thermoelectric applications, and investigate the detrimental effects of molecular vibrations on the efficiency of a molecular quantum dot as an energy converter. In addition, we consider the effects of a slow time-dependent modulation of applied voltages on the transport properties of a quantum dot and show how this can be used as a spectroscopic tool complementary to standard dc-measurements. Finally, we combine time-dependent driving with thermoelectrics in a double-quantum dot system - a nanoscale analogue of a cyclic heat engine - and discuss its operation and the main limitations to its performance.Comment: Review article submitted to PSS (b) for the special issue "Quantum transport at the molecular scale

Long-pulse KrCl laser with a high discharge quality \ud

The discharge quality and optimum pump parameters of a long-pulse high-pressure gas discharge excited KrCl laser are investigated. A three-electrode prepulse–mainpulse excitation circuit is employed as pump source. The discharge volume contains a gas mixture of HCl/Kr/Ne operated at a total pressure of up to 5 bar. For a plane–plane resonator, the divergence of both output laser beams is measured. A low beam divergence of less than 1 mrad is measured as a result of the very high discharge homogeneity. A maximum laser pulse duration of 150 ns (FWHM) is achieved for a pump duration of 270 ns (FWHM) and a power density of 340 kW cm-3. Pumping the discharge under optimum conditions employing a stable resonator results in a maximum specific energy of 0.45 J/l with a laser pulse duration of 117 ns and an efficiency of 0.63% based on the deposited energy

A hybrid metal/semiconductor electron pump for quantum metrology

Electron pumps capable of delivering a current higher than 100pA with sufficient accuracy are likely to become the direct mise en pratique of the possible new quantum definition of the ampere. Furthermore, they are essential for closing the quantum metrological triangle experiment which tests for possible corrections to the quantum relations linking e and h, the electron charge and the Planck constant, to voltage, resistance and current. We present here single-island hybrid metal/semiconductor transistor pumps which combine the simplicity and efficiency of Coulomb blockade in metals with the unsurpassed performances of silicon switches. Robust and simple pumping at 650MHz and 0.5K is demonstrated. The pumped current obtained over a voltage bias range of 1.4mV corresponds to a relative deviation of 5e-4 from the calculated value, well within the 1.5e-3 uncertainty of the measurement setup. Multi-charge pumping can be performed. The simple design fully integrated in an industrial CMOS process makes it an ideal candidate for national measurement institutes to realize and share a future quantum ampere

NASA preprototype redox storage system for a photovoltaic stand-alone application

A 1 kW preprototype redox storage system underwent characterization tests and was operated as the storage device for a 5 kW (peak) photovoltaic array. The system is described and performance data are presented. Loss mechanisms are discussed and simple design changes leading to significant increases in efficiency are suggested. The effects on system performance of nonequilibrium between the predominant species of complexed chromic ion in the negative electrode reactant solution are indicated

Ion drag EHD micropump with single walled carbon nanotube (SWCNT) electrodes

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Ion drag electrohydrodynamic (EHD) micropumps are promising in a number of micro-scale applications due to its small form factor, low power consumption, ability to work with dielectric heat transfer fluids, good controllability and absence of any moving parts. Ion drag EHD micro-pumps have been studied widely and the pressure head has been reported to depend on electrode material (i.e., work function), geometric configuration, electrode surface topology and applied electric field. One drawback of such pumps is the relatively low pressure head generation and high threshold voltage required for the onset of charge injection for practical applications. The presence of micro/nano features with sharp asperities on the emitter electrodes is likely to enhance the local electric field and charge injection significantly and thus, the pressure generation. The objective of this work is to investigate the effect of surface topology on the charge injection and pressure generation in HFE 7100. Experiments were performed using micropumps with smooth and single wall carbon nanotube (SWCNT) deposited on smooth gold electrodes. A lower threshold voltage, higher charge injection and pressure head was found for the micropump with SWCNT deposited on smooth electrodes compared to the no deposition case

Adiabatic response and quantum thermoelectrics for ac driven quantum systems

We generalize the theory of thermoelectrics to include coherent electron systems under adiabatic ac driving, accounting for quantum pumping of charge and heat as well as the associated work exchange between electron system and driving potentials. We derive the relevant response coefficients in the adiabatic regime and show that they obey Onsager reciprocity relations. We analyze the consequences of our generalized thermoelectric framework for quantum motors, generators, heat engines, and heat pumps, characterizing them in terms of efficiencies and figures of merit.Comment: Published versio

Parallel pumping of electrons

We present simultaneous operation of ten single-electron turnstiles leading to one order of magnitude increase in current level up to 100 pA. Our analysis of device uniformity and background charge stability implies that the parallelization can be made without compromising the strict requirements of accuracy and current level set by quantum metrology. In addition, we discuss how offset charge instability limits the integration scale of single-electron turnstiles.Comment: 6 pages, 4 figures, 1 tabl