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The flipped voltage follower (FVF), a variant of the common-drain transistor amplifier, comprising local feedback, finds application in circuits such as voltage buffers, current mirrors, class AB amplifiers, frequency compensation circuits and low dropout voltage regulators (LDOs). One of the most important characteristics of the FVF, is its low output impedance. In this tutorial-flavored paper, we...
Digital MIMO receivers featuring digitization at each element are critical for (massive) MIMO applications since they support complex space-time signal processing. However, the lack of spatial selectivity in the analog/RF domain necessitates high-dynamic-range analog-to-digital converters (A/Ds) to accommodate the uneven spatial power distribution, limiting the scale of such MIMO systems. This paper...
We describe a highly-programmable integrated sustaining amplifier for reconfigurable MEMS-referenced oscillators. The frequency response, voltage gain, and phase shift of the amplifier can be independently controlled using bias currents, thus enabling it to be interfaced with a variety of MEMS devices with resonant frequencies in the 10–120kHz range. The chip, which was designed in 0.5μm CMOS, also...
A platform has been developed to study intercellular communication in non-neural cells as it relates to developmental biology and morphogenetic bioengineering. The versatile platform uses laminar flow in a microfluidic channel to create a “sucrose gap” that forces electrical signaling through a cell monolayer. The intercellular communication in the cell network is detected through electrical impedance...
Impedance spectroscopy is a powerful technique that can be employed to determine the physical properties of different materials. In principle the technique can be implemented in the time domain using pulsed signal excitation rather than sweeping across frequencies. The advantage is particularly apparent when the measuring instrument is either traveling through the material medium rapidly, as in the...
Distributed on-chip low dropout (LDO) voltage regulators have become common due to the increasing number of on-chip voltage domains, dynamic voltage scaling, and the need for high quality power. Due to the current limitations of on-chip LDOs, hundreds of these regulators are required to deliver high quality power within modern high performance microprocessors. As the number of parallel connected LDOs...
The ever-increasing need for higher number of neural recording channels along with the stringent power and area requirements of a brain-implantable device, demand for ultra-compact and scalable channel architectures. In this paper, we will first briefly discuss the fundamental scaling issues of conventional AC- and DC-coupled neural front-ends. Next, we will analytically examine the feasibility of...
This paper proposes a lag-lead Active Voltage Positioning (AVP) technique that can be used in buck converters to minimize their output voltage transients during dynamic events, such as load pulses. The proposed technique is based on optimizing the output impedance of the converter across a wide range of frequencies, and therefore, output voltage transients in response to both narrow and wide load...
This paper presents a new approach towards the design and implementation of high-throughput impedimetric screening for life science applications. Herein, we propose a new cell-on-chip model for cellular analysis. A low complexity platform was developed to demonstrate the advantages of this model for cellular analysis. This low cost platform consists of an array of optically transparent electrodes...
The equivalent circuit model parameters of the barrel-stave flextensional transducer and array are calculated using the circuit principle together with the finite element, boundary element method and the measured results. The electro-acoustic characteristics of the transducers and arrays are analyzed by the obtained equivalent circuit model. The resonant frequencies and admittance curves of the transducers...
In this paper we present a systematic method to synthesize and analyze fully differential input-output filters using two port networks. Transfer functions, input and output impedance can be evaluated for various impedances and transmission matrices varied to investigate the filter's performance. Experimental and simulated results in Cadence are provided.
This paper presents a static non-linearity correction technique exemplary applied on a 10-bit source series terminated digital-to-analog converter (DAC) implemented in 180 nm CMOS. The proposed technique proves for the first time, that an undesired power supply and package resistance can be turned into a benefit by canceling non-linearity effects introduced by the MOSFET switches within the source...
A new Time Domain Impedance Probe (TDIP) is presented in this paper. The new instrument is able to make measurements of absolute electron density and electron neutral collision frequency in the ionosphere at temporal and spatial resolutions not previously attained. A single measurement is made in 100 microseconds, which yields an instantaneous spatial resolution of 0.1 meters for sounding rocket experiments...
In this paper, a design architecture of a compact, concurrent quadband Doherty Power Amplifier (DPA) is proposed that relies on a new quadband band-pass filter comprising the input matching network. The filter — based on Quarter Wave Open Stubs (QWOS) at the desired operation frequencies — is embedded within the output arms of a wideband power divider to create the targeted four arbitrary frequencies...
Analysis methods for DC power interfaces using techniques built around the Nyquist stability criteria have previously been utilized to create system level specifications to ensure the stability of interconnected systems. This paper extends these concepts to not just ensure stability, but to also ensure a guaranteed maximum level of voltage and current perturbation within the system. The technique...
Well established cable network diagnosis systems rely on reflectometry and transferometry principles to detect faults using specific signals within a frequency spectrum of a few hundreds MHz only. Huge performance improvements in terms of precision and sensitivity can be achieved with higher frequencies and signal modulation, hence revealing phase and amplitude response of the potential impedance...
The proposed circuit aims to harvest energy from freight railcars, in which a three-phase electromagnetic generator (EMG) is used to harvest kinetic energy. The key idea of the proposed circuit is to extract maximum power from the EMG through impedance matching until the charge level of the battery reaches 90%. Once, the battery reaches the charge level, it switches the operation mode and regulates...
Electrochemical Impedance Spectroscopy is widely popular in the medical field where it is often referred to as bioelectrical impedance analysis (BIA) used to analyze biological materials as well as characterization of body fluids. It is a complex technique requiring expensive equipment that is also large making it difficult to integrate into small form-factor systems that are hand-held, wearable and...
Frequency domain methods of extracting equivalent series resistance (ESR) and equivalent series capacitance (ESC) for on-die decoupling capacitors using spice-like simulators are briefly reviewed. A concise method is then proposed for converting the frequency domain equivalent ESR and ESC to an approximate broadband equivalent circuit which can be readily used in time domain simulations. The method...
This paper presents a novel architecture for a kilo-ohm to giga-ohm pseudo-resistor (PR), based on transistors operating in subthreshold with a fixed-Vgs configuration. This PR when used in an RC filter has a very low and constant settling time regardless of the programmed pole frequency. The proposed PR takes advantage of bootstrapping to improve its tuning range. By defining a constant VGs for the...
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