Adam Boura

NMOS and PMOS Translinear Multiplying Cell for Current-Mode Signal Processing

The paper describes NMOS and PMOS translinear cell which multiplies the current signals and which can be used for the current-mode signal processing. The translinear cell consists of NMOS or PMOS transistors that are treated in the sub-threshold conduction region. In this region the transistors exhibit an exponential dependency of the drain current versus the gate voltage and thus the translinear principle can be used for description of the functionality. Operation region of the cell is limited by the validity of the exponential dependency and also by the transistors leakage currents. Significant error is also induced by the auxiliary current mirrors which are biasing the cells. Channel length modulation effect causes error of the input signals and thus the output signal is affected by the multiplicative error. The paper presents basic idea of the multiplying cell, presents results of simulations in CADENCE and also presents results of measurements on real structure composed using discrete transistors.

Simple wireless A/D converter for isolated systems

Motivation for this paper is to present possible solution for measuring analog values in isolated systems without batteries. It can be suitable for biomedical probes, enclosed systems such as tubes, extreme temperature environments etc. The system is considering no batteries because of their finite lifetime, toxicity or an extreme temperatures environment that is improper for the batteries. System thus must be powered wirelessly and also the information must be transmitted without any wires. It is not necessary a long distance for this powering. Usually it is enough to transfer up to 20 cm. The paper presents basic theory needed for a design of the powering, communication and also the analog to digital converter. The converter is presented consisting of discrete devices and also it is presented scheme for chip realization using the 500 nm CMOS technology.

Design and characterization of NCD piezoresistive strain sensor

Nanocrystalline Diamond (NCD) is a very promising material for fabrication of high-temperature devices because of its unique mechanical and electrical properties. The prospective of using diamond is not only in sensors (MEMS) but in RF and power electronic as well. The strain gauges based on nanocrystalline diamond layers have been successfully designed and fabricated using mainly domestic technological background. The CoventorWare FEM calculations of the mechanical stress and geometrical deformations of a 3-D structure are used for a proper localization of the piezoresistor on the carrying substrate. The boron-doped piezoresistive sensing element was realized using a directed patterned growth of NCD film on SiO2/Si by microwave plasma enhanced chemical vapor deposition (CVD). Cantilever beam configuration was used for sensor characterization. The sheet resistance of tensometric layers as well as contact edge resistivity were measured by Transmission Line Method (TLM). The gauge factor of boron-doped NCD films was investigated in the range from room temperature up to 250 °C and from 0 to 1 N of applied force.

Potentiality of the inductive powering for measurement in the enclosed systems

Paper presents wireless powering and signal transfer solution using the inductive coupling. It can be suitable for enclosed systems that are isolated from the surroundings and where the batteries cannot be used. It can be used for biomedical probes, probes bricked in to the wall for long-term monitoring, extreme temperature environment measurement etc. The powering is provided by the near magnetic field. The serial and parallel resonances are considered in the design in order to increase the voltage transfer. Voltage levels, power transfer efficiency and signal modulation effects are studied up to distance of 30 cm. Presented principle of powering and communication is similar to the RFID systems (Radio Frequency Identification). The main contribution of this paper is powering potentialities and distance limits prediction of this powering strategy. The simple coils are considered. Special converter is presented for this purpose.

Characterization of gas sensor with polyaniline film

The aim of the paper is to present results of design gas sensor with different form of polyaniline active layer for toxic gases detection. Sensing of toxic gases is very important in many applications. Automotive, defence, aerospace, agriculture, chemical industry, medicine, environmental, food and drink are many important markets for chemical and biological sensors. The advantages of resistive sensors are easy fabrication, simple operation and low production cost. Using of polymer film causes that this sensor is not required heating of active layer. This leads to reduce power consumption. Active layer is operated at room temperature.

Intelligent Sensor Network for Physical Quantities Measurement

The article solves the design and implementation of a simple intelligent sensor network for physical quantities measurement. The system uses wireless data transmission. Sensor network is designed as a basic element of the ZigBee network. Each unit has a sensor attached to a microcontroller. The system is controlled by PC, the variable arrangement can be used. The different type of the sensor can be used. The system can be extended to other types of sensors for measuring the chemical variables. The data transfer from PC can be transmitted by internet.

Wireless sensor network control system

The core of the paper is the control system with a few electronic blocks (control, actuator, software, and RF wireless communication). The control block drives operations in the system, the wireless block ensures communication, and data transfer, the actuator part is drived by control block. The software drives all operations in the system. Sensors ensure basic information about environment. The number of sensor can be variable. The control block cooperates with wireless sensors, and wireless actuators. The heart of the system is the control microprocessor. The system communicates with PC, mobile phone etc. There was used a new architecture of a multisensor system for physical measurement using wireless data transfer in the paper. Different control software was designed for wireless parts.

Digitally Tunable Section for an Analog Current-Mode Predistortion

The paper describes a circuit system which is able to process an analog current mode signals. It is intended to use it as a preamplifier and corrector of the transfer characteristic of some kind of sensor. The circuit is based on the sub-threshold CMOS multiplying cells. Those cells are interconnected by the current mirrors to form a circuit with desired transfer characteristic. There are two ways how to use this circuit. It can be used for direct linearization (pre-distortion) of the signal from the sensor or it can be encircled by a negative feedback in order to realize the inverse function. The circuit is dedicated for slow signals and for extremely low power applications. The transfer characteristic is tunable aid four ten-bit digital to analog converters. The program CADENCE and the CMOS 180 nm technology were used for simulations.

Translinear Subthreshold MOS Filter for the Wireless Sensors Applications

The work describes a design of the filter using log-domain CMOS technology. Filter only consists of capacitances and CMOS transistors in the week inversion mode and they are treated in the subthreshold conduction region. Low-pass, band-pass and high-pass filter is considered in the design. The transfer function of the filter is determined by the feedback around its input and output. My design is based on demand to have a universal building block which is able to filter the frequency band from DC to radio frequencies. This building block is represented by the log-domain differentiator. The frequency band and the transfer function of the filter is determined only aid few devices connected to this building block. It is intended to use these current-mode filters in the design of the wireless sensor systems. In these applications the low-pass filters are usually used as an antialiasing filter before the signal is sampled. Also the radio frequency part of the circuit uses the filters. The program CADENCE and 0.18 mum CMOS technology were used for simulations

Direction Sensitivity Matrix with PLL Temperature Sensor

In the paper there is presented temperature transducer with PLL signal processing of sensor data. The principle of temperature sensor is based on the MOS structure behaviour in the temperature range. The strong and weak inversion modes are used. There is used matrix of temperature sensors in the design of air flow sensor. Various arrangements of temperature structure are designed. The new circuits design is used