Gianluca Barile

Full range analog Wheatstone bridge-based automatic circuit for differential capacitance sensor evaluation

Summary nIn this paper, an integrable novel fully analog Wheatstone bridge-based interface for differential capacitance estimation is presented. Its working principle takes advantage of the modified De-Sauty AC bridge configuration being employed only by two capacitors and two resistors. A feedback loop controls one of the resistors (e.g. a voltage-controlled resistor), to obtain an evaluation of the differential capacitance variation on a full range, thanks to a general but very simple formula that considers both the ‘auto-balancing’ and the bridge ‘out-of-equilibrium’ ranges. The proposed interface shows a satisfactory accuracy, being the percentage relative error within 0.45% for the experimental results. Copyright

A standard CMOS bridge-based analog interface for differential capacitive sensors

This work describes an analog electronic interface, based on a modified De Sauty AC bridge, performing a differential capacitive sensor estimation. A suitable feedback loop tunes a Voltage Controlled Resistor to balance the bridge. The electronic circuit has been designed in a standard integrated CMOS technology (AMS 0.35μm) with a low supply voltage (±1.5 V) and a reduced power consumption (lower than 4mW). PSpice simulation results show a very good agreement with theoretical expectations. The output voltage accuracy shows a 0.03V maximum absolute error for a range of ±50% of sensor variations from its baseline value. Very small baseline values are allowed (tens of μF).

A Novel Electronic Interface for Micromachined Si-Based Photomultipliers

In this manuscript, the authors propose a novel interface for silicon photomultipliers based on a second-generation voltage conveyor as an active element, performing as a transimpedance amplifier. Due to the absence of internal feedback, this solution offers a static bandwidth regardless of the tunable gain level. The simulation results have shown good performances, confirming the possibility of the proposed interface being effectively used in different scenarios. A preliminary hybrid solution has also been developed using second-generation current conveyors and measurements conducted on an equivalent discrete-elements board, which is promising.

Class-AB current conveyors based on the FVF

We propose a novel class-AB second-generation Current Conveyor (CCII) based on the class-AB Flipped Voltage Follower (FVF) topology, and compare it with a class-A CCII based on the conventional FVF. The AB-FVF is capable of driving larger capacitive loads, showing faster settling. Furthermore, it can drive the Z output with currents larger than the biasing ones, improving power efficiency. A modification of a previously published FVF is also introduced to improve the compensation of the frequency response.

Power-efficient dynamic-biased CCII

In this work a dynamic biasing circuit for current conveyor (CCII) applications is proposed and discussed with circuitry details. This solution, applied for the first time to current-mode circuits, allows to decrease the steady state power consumption of the considered circuit, minimally affecting its performance. The dynamic biasing solution here conceived is able to sense the input signal providing an extra current to the CCII only when an input voltage variation occurs. The proposed conveyor shows a good transient response and allows to combine the needs of both low-power and high slew-rate characteristics that are mandatory in many practical applications and wireless systems. A case-study is also illustrated with simulation results.

Integrable Sensor System for Live Monitoring of Loudspeaker Performances

We here present a dedicated system capable of compensating loudspeaker distortion due to driver working condition or apparatus aging. The proposed monitoring system is formed by a reduced number of sensors that monitor the loudspeaker by a digital signal processing architecture (DSP) which performs a feedback to the loudspeaker amplifier so balancing its gain. All the sensors are designed to not interfere with output sound quality.

Wireless Smart Parking Sensor System for Vehicles Detection

The proposed paper shows a novel and feasible solution for the realization of a smart-parking system. The proposed parking sensor circuit represents a robust and low cost solution for the automotive market to perform parking operations faster and simpler. The sensing strategy is based on both the electromagnetic coupling with the car platform and on an innovative dedicated algorithm implemented in a digital sensor interface for data acquisition and manipulation.

CCII-Based Linear Ratiometric Capacitive Sensing by Analog Read-Out Circuits

Two electronic interfaces performing a differential (or ratiometric) sensor capacitance to voltage conversion are here presented. The output signal is proportional to the measurand variation x. The two read-out circuits differ themselves in their input stage: the first has an input current-to-voltage conversion, while the second one employs an input voltage source. Both of the solutions utilize commercial second generation current conveyors (CCIIs) as active blocks, in particular AD844. Theoretical analysis, simulated and experimental results have shown a good accuracy. Considering a capacitance variation due to the relative distance change, interface sensitivity (S) and resolution (res) values are constant and satisfactory: for the first solution, S = 8.54 V/μm and res = 674 pm (capacitance resolution value is 89.85 fF, that is −79 dB), while, for the second one, S = 8.13 V/μm and res = 814 pm (capacitance resolution value is 108.5 fF, that is −77 dB).

Voltage-Mode Analog Interfaces for Differential Capacitance Position Transducers

A fully-analog integrated electronic interface for the detection and measurement of differential capacitive position sensors is shown. The read-out circuit, performing a differential capacitive to voltage conversion, has been developed in a standard 0.35 μm CMOS technology with low-voltage/low-power characteristics. The interface has shown a good accuracy, in particular the relative percentage error is lower than 0.8% for the simulations of the integrated solution. When compared to other solutions in the literature, sensitivity (S) and resolution (res) data on a practical case-study of position sensor are satisfactory so validating the architecture to be a good candidate as first stage in analog front-ends for differential capacitive sensor data measurements.