Analog Mixed Signal Based SoC for Measurement of AC Electrical Conductivity of Water

N recent years, the analog and mixed signal design, an innovative VLSI technology, is capable to satisfy the prime requirement for ubiquitous embedded system, which is playing a dominant role in flourishing dedicated VLSI based embedded technology [1].The dynamic reconfigurability is the important feature of many mixed signal devices. Due to unique feature, reconfigurability, this innovative technology, mixed signal, has remarkable application in various field, from simple domestic appliances to critical space shuttle application. Therefore, many investigators shows their prominence on this reconfigurability to develop the ubiquitous embedded system [2], [3]. However, in the field of instrumentation especially precision measurement and controlling of various chemical as well as physical parameters, such as pH, dissolved oxygen, temperature, electrical conductivity (EC), etc. is the crucial task [4], [5]. The many investigators are opting suitable microprocessors and microcontrollers of renowned families, ARM, PIC, AVR ATmega etc., of commendable features to design an embedded system for such parameter measurement [6], [7]. But, all these embedded systems realise the concept of Systemon-Board (SoB) design as analog design is always off-chip. An embedded system for measurement of electrical conductivity of the soil using PIC 18F4550 microcontroller is developed by SalehaBegum et al [8], where preamplifier, precision rectifier and level translator for PC via USB interface are off-chip. Rajendran et al have developed 8031 microcontroller based embedded system for temperature compensated electrical conductivity, wherein precision rectifier, ADC0808, PPI 8255 and RS232 transmitter/receiver interface are off-chip, to measure electrical conductivity they deployed the modified AC Wheatstone Bridge network [9]. Postolache et al have developed multi-sensing embedded system employing two PIC 18F4520 for water quality assessment [6]. They reported analog Data Acquisition System (DAS) for temperature dependent electrical conductivity measurement. Deploying Agilent 34401A Safarova et al measured the electrical conductivity of electrotextiles material [10]. Lorentz force sigmometry technique is employed by Uhlig et alfor the contactless measurement of the specific electrical conductivity of a solid body and fluid [11]. Jaimes-Ponce et al have implemented PIC 18F4550 based embedded system for hydroponic system of nutritious film to control flow and electrical conductivity of nutritious solution in growth channel [12], where DAS is developed around AD620. Pabiania et al have developed genetic algorithm in MATLAB prototype hydroponic system using PIC microcontroller to measure and monitor pH and electrical conductivity [13]. The four node neural network system using PIC18F452 for measurement of I