FVF-Based Low-Dropout Voltage Regulator with Fast Charging/Discharging Paths for Fast Line and Load Regulation

A new internally compensated low drop-out voltage regulator based on the cascoded flipped voltage follower is presented in this paper. Adaptive biasing current and fast charging/discharging paths have been added to rapidly charge and discharge the parasitic capacitance of the pass transistor gate, thus improving the transient response. The proposed regulator was designed with standard 65-nm CMOS technology. Measurements show load and line regulations of 433.80 μV/mA and 5.61 mV/V, respectively. Furthermore, the output voltage spikes are kept under 76 mV for 0.1 mA to 100 mA load variations and 0.9 V to 1.2 V line variations with rise and fall times of 1 μs. The total current consumption is 17.88 μA (for a 0.9 V supply voltage).Ministerio de Economía y Competitividad TEC2015-71072-C3-3-RConsejería de Economía, Innovación y Ciencia. Junta de Andalucía P12-TIC-186

Electronic control circuits: A compilation

A compilation of technical R and D information on circuits and modular subassemblies is presented as a part of a technology utilization program. Fundamental design principles and applications are given. Electronic control circuits discussed include: anti-noise circuit; ground protection device for bioinstrumentation; temperature compensation for operational amplifiers; hybrid gatling capacitor; automatic signal range control; integrated clock-switching control; and precision voltage tolerance detector

An enhanced recycling folded cascade OTA with a positive feedback

In this paper an enhanced fully differential recycling folded cascode operational trans conductance amplifier that achieves higher DC gain with same power and area as that of recycling folded cascode OTA is discussed. Generally, the output impedance of the cascode amplifier depends on the current flowing into the cascode node. Hence, in order to increase the DC gain of the conventional Recycling Folded Cascode OTA the modification is done at the cascode node. The proposed enhanced fully differential RFC OTA is implemented in strong inversion using gm/Id methodology. The design is carried out using UMC180nm technology and studied through simulation. From simulation, we found an increase in DC gain of 9dB, 14dB, and 24dB is achieved without changing the Unity Gain Bandwidth

Quantum shot noise in mesoscopic superconductor-semiconductor heterostructures

Shot noise in a mesoscopic electrical conductor have become one of the most attentiondrawing subject over the last decade. This is because the shot-noise measurements provide a powerful tool to study charge transport in mesoscopic systems [1]. While conventional resistance measurements yield information on the average probability for the transmission of electrons from source to drain, shot-noise provides additional information on the electron transfer process, which can not be obtained from resistance measurements. For example, one can determine the charge ‘q’ of the current carrying quasi-particles in different systems from the Poisson shot noise SI = 2q�I� [2] where �I� is the mean current of the system. For instance, the quasi-particle charge is a fraction of the electron charge ‘e’ in the fractional quantum Hall regime [3, 4, 5]. The multiple charge quanta were observed in an atomic point contact between two superconducting electrodes [6]. Shot-noise also provides information on the statistics of the electron transfer. Shot noise in general is suppressed from its classical value SI = 2e�I�, due to the correlations. In mesoscopic conductors, due to the Pauli principle in fermion statistics, electrons are highly correlated. As a results, the noise is fully suppressed in the limit of a perfect open channel T = 1. For the opposite limit of low transmission T � 1, transmission of electron follows a Poisson process and recovers the Schottky result SI = 2e�I� [2]. For many channel systems, shot-noise is suppressed to 1/2 × 2e�I� for a symmetric double barrier junction [7, 8], to 1/3 in a disordered wire [9, 10, 11, 12, 13, 14] and to 1/4 in an open chaotic cavity [15, 16, 17]. When a superconductor is involved, the shot-noise can be enhanced by virtue of the Andreev reflection process taking place at the interface between a normal metal and a superconductor. In some limiting cases, e.g. in the tunneling and disordered limit, the shot-noise can be doubled with respect to its normal state value [18, 19, 20, 21]. One of the main results of this thesis is an extensive comparison of our experimental data on conductance and shot noise measurements in a S-N junction with various theoretical models. In addition to measure shot-noise in a two-terminal geometry, one can also perform the fluctuation measurements on multi-terminal conductors. Whereas shotnoise corresponds to the autocorrelation of fluctuations from the same leads, crosscorrelation measurements of fluctuations between different leads provide a wealth of new experiments. For example, the exchange-correlations can be measured directly from these geometry [22]. Experimental attempt in mesoscopic electronic device was the correlation measurements [14, 23] on electron beam-splitter geometry [24] which is the analogue to the Hanbury-Brown Twiss (HBT) experiment in optics. In their experiment, Hanbury-Brown and Twiss demonstrated the intensity-intensity correlations of the light of a star in order to determine its diameter [25]. They measured a positive correlations between two different output photon beams as predicted to the particles obeying Bose-Einstein statistics. This behavior is often called ‘bunching’. On the other hand, a stream of the particles obeying Fermi-Dirac statistics is expected to show a anti-bunching behavior, resulting in a negative correlation of the intensity fluctuations. Latter one was confirmed by a Fermionic version of HBT experiments in single-mode, high-mobility semiconductor 2DEG systems [14, 23]. Whereas in a single electron picture, correlations between Fermions are always negative1 (anti-bunching), the correlation signal is expected to become positive if two electrons are injected simultaneously to two arms and leave the device through different leads for the coincident detection in both outputs2. One simple example is the splitting of the cooper pair in a Y-junction geometry in front of the superconductor. Fig.1.1 shows the possible experimental scheme of the correlation measurement as described here and the sample realized in an high-mobility semiconductor heterostructures. Since all three experiments were done3, only one left unfolded, ‘The positive correlations from the Fermionic system’. The main motivation of this thesis work was to find a positive correlations in the device shown in Fig.1.1. In a well defined single channel collision experiment on an electron beam splitter, it has theoretically been shown that the measured correlations are sensitive to the spin entanglement [29, 30]. This is another even more exciting issue and we would like to mention that the experimental quest for positive correlations is important for the new field of quantum computation and communication in the solid state, [31, 32] in which entangled electrons play a crucial role. A natural source of entanglement is found in superconductors in which electrons are paired in a spin-singlet state. A source of entangled electrons may therefore be based on a superconducting injector.[33, 34, 27, 35, 36, 37, 38, 38, 39, 40, 41] Even more so, an electronic beamsplitter is capable of distinguishing entangled electrons from single electrons.[29, 42] However, the positive correlations have not been observed in solid-state mesoscopic devices until today. This thesis is organized as follows. Chapter 2 is devoted to the theoretical background of the electrical transport and the current fluctuations. We introduce the basic concept of electrical transport and the shot noise in normal state and superconductor-normal metal (S-N) junction. We also briefly review the theoretical proposals and arguments about the current-current cross-correlations in threeterminal systems. In Chapter 3, we describe the sample fabrication techniques which have been done in our laboratory such as e-beam lithography, metallization and etching. We present also the characterization of our particular system, niobium (Nb) / InAs-based 2DEG junction. Chapter 4 describes the reliable low-temperature measurement technique for detecting the noise. We characterize our measurement setup using a simple RC-circuit model. In Chapter 5, our main results about the shot noise of S-N junction are presented in detail

Design and Simulation of Two Stage Wideband CMOS Amplifier in 90 NM Technology

Design and simulation of 7 GHz CMOS wideband amplifier(CMOSWA) using a modified cascode circuit realized in  90-nm CMOS technology is presented here. The proposed system consists of two stages, namely a modified folded cascode and an inductively degenerated common source amplifier. The circuit is experimented with and without a feedback network. This work discusses the performance variation as a function of reactive components, and the initial stage results in 22 dB gain,2.6 GHz bandwidth, and 40GHz unity gain-bandwidth. The circuit without the feedback network exhibits 30.7dB gain,4.8GHz bandwidth(BW), and 10GHz unity-gain bandwidth(UGB). The reactive feedback network's inclusion helped to achieve 38.7 dB gain, 6.95GHz BW, 30GHz UGB, and 55o phase margin. The circuit consumes 1.4mW power from a 1.8V power supply. Simulation results of the proposed circuit are comparable and better than the reported wideband designs in the literature. Realization of our proposed circuit would add value to the area of wideband amplifier design