A Second-Generation Voltage-Conveyor-Based Interface for Ultrasonic PVDF Sensors

Abstract

Exploiting the transmission and reception of low frequency ultrasounds in air is often associated with the innate echolocating abilities of some mammals, later emulated with sophisticated electronic systems, to obtain information about unstructured environments. Here, we present a novel approach for the reception of ultrasounds in air, which exploits a piezopolymer broadband sensor and an electronic interface based on a second-generation voltage conveyor (VCII). Taking advantage of its capability to manipulate both voltage and current signals, in this paper, we propose an extremely simple interface that presents a sensitivity level of about −100 dB, which is in line with commercially available references. The presented results are obtained without any filtration stage. The second-generation voltage conveyor active device is implemented through a commercially available AD844, with a supply voltage of ±15 V.

A Survey on Current-Mode Interfaces for Bio Signals and Sensors

“…An alternative representation with a voltage source is clearly possible, but it is preferable to represent the sensor as a current generator in this context because its impedance is typically somewhat higher than the impedance of the Y input port of a VCII, a fact that allows directly interfacing the spiral shaped PVDF sensor to the VCII. This has been exploited in [ 46 ], where a circuit similar to that in Figure 13 a for a SiPM has been applied to a spiral-shaped omnidirectional PVDF sensor specifically designed to receive ultrasounds in air in a wide frequency range (20–80 kHz) [ 97 ]. The designed circuit displays a transimpedance gain of 86 dBΩ and an overall power consumption of about 6 mA.…”

“…In [ 46 ], a circuit to perform a noise filtering function in addition to transimpedance amplification was developed to obtain a purified version of the received signal, depicted in Figure 15 . This goal was achieved using , , , to obtain a second-order band-pass filter, with a transfer function given by or, alternatively, using , , , to obtain a second-order low-pass filter with transfer function where the sensor impedance has been considered negligible in calculations.…”

“…The main current-mode analog blocks are the second-generation current conveyor (CCII) and its dual, the second-generation voltage conveyor (VCII). These blocks have been successfully applied to the realization of a variety of analog signal processing functions [ 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. For example, in [ 31 ] a current-mode full-wave bridge rectifier has been developed; in [ 32 , 40 , 42 ] the realization of various filter functions using VCII is shown; and in [ 33 , 53 ] current-mode oscillators are described.…”

Implementation of a Double-Path Flipped Voltage Follower Cell for Voltage Conveyors

“…Based on the aforementioned features, VCII was used to design some applicable building blocks such as gyrators [3], multipliers [6], oscillators [7], filters [8,9], and inductors [10]. Moreover, analog circuits including readout circuits, integrators, differentiators, voltage amplifiers, and current-tovoltage converters were recently realized using VCIIs [5,11,12]. The class-A VCIIs are inappropriate for low-power design due to their low current drive capability, while class-AB structures provide a high current drive capability along with a low quiescent current [4].…”

Reconfigurable Voltage-Mode First-Order Multifunction Filter Employing Second-Generation Voltage Conveyor (VCII) With Complete Standard Functions and Electronically Controllable Modification

“…It is obvious that a new active building block with low-impedance voltage output capability is useful for many analog signal processing applications like analog filters, inverse filters, and sinusoidal oscillators, etc. Second-generation voltage conveyor (VCII) is a versatile block [8], [9], [10], which is the dual of CCII, and it has been used for applications [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31] requiring lowimpedance voltage output. This new ABB has an advantage over CCII and previous current-mode ABBs since it can process signals in the current domain and output signals in both voltage and current.…”