Biasing

About: Biasing is a research topic. Over the lifetime, 29422 publications have been published within this topic receiving 301035 citations.

A CMOS bandgap reference without resistors

Abstract: Bandgap references add the forward bias voltage across a pn diode with a voltage that is proportional to absolute temperature (PTAT) to produce an output that is insensitive to changes in temperature. The relative weighting of the voltages added is usually adjusted by trimming the ratio of two resistors. Although inexpensive resistors of suitable values are available in analog CMOS processes, the area of such resistors is increased in standard digital processes because silicide is often used to reduce the sheet resistance of the polysilicon and diffusion layers. As a result, the length and area of the required resistors is increased, increasing not only the cost, but also the susceptibility of the reference operation to substrate noise coupling. One way to overcome this problem is to use an extra mask to selectively block the silicide, but this mask also increases the cost. This paper presents a circuit solution to the above problem: a bandgap reference without resistors. It uses only MOS transistors biased in saturation or cutoff. The devices biased in saturation operate in strong inversion, for which accurate device models are usually available, simplifying the design process, especially in digital CMOS technologies.

Direct Observation of Macroscopic Charge Quantization

Abstract: The circuit formed by a nanoscale tunnel junction in series with a capacitance and a voltage source is the building block of most multi-junction circuits of single electronics. The state of this “single electron box” is entirely determined by the numbern of extra electrons on the intermediate “island” electrode between the junction and the capacitance. We have fabricated such a system and measured the charge on the junction capacitance, which is directly related to the average value ofn, as a function of the bias voltage using a Fulton-Dolan electrometer. At low temperature, the junction charge followed thee-periodic sawtooth function expected from the theory of macroscopic charge quantization. Strikingly,e-periodic variations were also observed when the box was superconducting. The thermal rounding of the sawtooth function is well explained by a simple model, except at the lowest temperatures.

Voltage tunable varactors and tunable devices including such varactors

Abstract: A voltage tunable dielectric varactor includes a substrate having a low dielectric constant and having generally planar surface, a tunable ferroelectric layer positioned on the generally planar surface of the substrate, and first and second electrodes positioned on a surface of the tunable ferroelectric layer opposite the generally planar surface of the substrate. The first and second electrodes are separated to form a gap therebetween. The varactor includes an input for receiving a radio frequency signal and an output for delivering the radio frequency signal. A bias voltage applied to the electrodes changes the capacitance of the varactor between the input and output thereof. Phase shifters and filters that include the varactor are also described.

Tunnel diode oscillator for 0.001 ppm measurements at low temperatures

Abstract: The results of a systematic study of the design considerations of a low‐temperature tunnel diode oscillator are presented. The calculated circuit performance satisfactorily describes the measured frequency noise and dependence on bias voltage, magnetic field, and temperature. The overall performance allows measurement of changes in the resonant frequency of an LC circuit with a precision of 0.001 ppm. One can thereby detect extremely small changes in a number of material properties such as thermal expansion, surface impedance, and electric and magnetic susceptibilities.

Fabrication and characterization of ultraviolet-emitting diodes composed of transparent p-n heterojunction, p-SrCu2O2 and n-ZnO

Abstract: An ultraviolet light-emitting diode (UV-LED) was realized using a p-n heterojunction composed of the transparent oxide semiconductors p-SrCu2O2 and n-ZnO. A Ni/SrCu2O2/ZnO/ITO multilayered film was epitaxially grown on an extremely flat YSZ (111) surface by a pulsed-laser deposition technique. SrCu2O2 (112) was preferentially grown on ZnO (0001) at 350°C, while the preferential plane was changed into the (100) when the temperature was increased to 600 °C. The grown films were processed by conventional photolithography followed by reactive ion etching to fabricate heterojunction diodes. The resulting devices exhibited rectifying I-V characteristics inherent to p-n junctions. A relatively sharp electroluminescence band centered at 382 nm, attributed to transitions associated with exciton-exciton collision or electron-hole plasma in ZnO, was generated by applying a forward bias voltage greater than the turn-on voltage of 3 V. UV-LED performance characteristics such as threshold current and conversion efficie...