A Current-Mode Position Sensitive Circuit

A novel technique to implement mesh-type position sensitive devices using current-mode analog VLSI is presented. By taking advantage of local analog computation this approach allows to create extremely compact circuit implementations. While in conventional approaches most sensor characteristics are adjusted by setting process parameters, our technique is fully electronically tunable and suitable to be implemented in general purpose CMOS technology. We have verified experimentally our idea designing and fabricating via MOSIS a 20 element 1D position circuit. Test results are presented demonstrating nonlinearity below 2.2% for currents in the range of 5pA to 10nA

Fast and Reliable Modeling of Piezoelectric Transducers for Energy Harvesting Applications

The paper presents a fast and reliable model identification technique for piezoelectric transducers based on an equivalent electromechanical circuit easily implementable on SPICE-like simulation tools. Model parameter extraction is simple and requires just standard and inexpensive laboratory equipment. Indeed, the equivalent circuit representation permits the evaluation of the response of a real energy harvesting system, where the electronic load is a synchronized switching converter which usually causes a significant feedback on the mechanical part of the system during energy extraction. Both simulation and measurements show that the damping effect is particularly important near resonance, where the adopted model is able to fit the experimental data and provides a more realistic description of the behavior of the system

A 32 mV/69 mV input voltage booster based on a piezoelectric transformer for energy harvesting applications

This paper presents a novel method for battery-less circuit start-up from ultra-low voltage energy harvesting sources. The approach proposes for the first time the use of a Piezoelectric Transformer (PT) as the key component of a step-up oscillator. The proposed oscillator circuit is first modelled from a theoretical point of view and then validated experimentally with a commercial PT. The minimum achieved start-up voltage is about 69 mV, with no need for any external magnetic component. Hence, the presented system is compatible with the typical output voltages of thermoelectric generators (TEGs). Oscillation is achieved through a positive feedback coupling the PT with an inverter stage made up of JFETs. All the used components are in perspective compatible with microelectronic and MEMS technologies. In addition, in case the use of a ∼40 μH inductor is acceptable, the minimum start-up voltage becomes as low as about 32 mV

Diffusion networks for on-chip image contrast normalization

A new method for normalizing and quantizing images is presented. The method is based on calculating a local reference frame for the image gray levels. The levels of the reference frame are calculated using biased diffusions that are linked to the original image. The method is conceived to be integrated with sensing elements on the image plane of a camera. Its mathematical properties are analyzed and its performance is experimentally demonstrated. A circuital implementation has been designed, constructed and tested; it consists of a 20 nodes 1-D non-linear resistive grid. Experimental results are shown

A Current-Mode Position Sensitive Circuit

A novel technique to implement mesh-type position sensitive devices using current-mode analog VLSI is presented. By taking advantage of local analog computation this approach allows to create extremely compact circuit implementations. While in conventional approaches most sensor characteristics are adjusted by setting process parameters, our technique is fully electronically tunable and suitable to be implemented in general purpose CMOS technology. We have verified experimentally our idea designing and fabricating via MOSIS a 20 element 1D position circuit. Test results are presented demonstrating nonlinearity below 2.2% for currents in the range of 5pA to 10nA

A low-noise transimpedance amplifier for BLM-based ion channel recording

High-throughput screening (HTS) using ion channel recording is a powerful drug discovery technique in pharmacology. Ion channel recording with planar bilayer lipid membranes (BLM) is scalable and has very high sensitivity. A HTS system based on BLM ion channel recording faces three main challenges: (i) design of scalable microfluidic devices; (ii) design of compact ultra-low-noise transimpedance amplifiers able to detect currents in the pA range with bandwidth >10 kHz; (iii) design of compact, robust and scalable systems that integrate these two elements. This paper presents a low-noise transimpedance amplifier with integrated A/D conversion realized in CMOS 0.35 µm technology. The CMOS amplifier acquires currents in the range ±200 pA and ±20 nA, with 100 kHz bandwidth while dissipating 41 mW. An integrated digital offset compensation loop balances any voltage offsets from Ag/AgCl electrodes. The measured open-input input-referred noise current is as low as 4 fA/Root Hz at ±200 pA range. The current amplifier is embedded in an integrated platform, together with a microfluidic device, for current recording from ion channels. Gramicidin-A, alpha-haemolysin and KcsA potassium channels have been used to prove both the platform and the current-to-digital converter