Development of Inverter Circuits with Dual Control Subchannel Areas of Integral CMOS Sensor Element

The use of an integrated sensor element as an addition of inverter, which converts the resistance of a sensitive element into the level of the output pulse signal, is investigated. Inverter circuits with different control options for sub-channel areas of MOS transistors are modeled in the LTSpice program. Based on the simulation results, dependencies graphs of the output signal amplitude on the resistance of a sensitive element and sensor’s sensitivity are drawn, and the shapes of the output signals are shown.

Compact Charge-Controlled Memristance Simulator with Electronic/Resistive Tunability

The work endeavors to realize a single Voltage Differencing Current Conveyor (VDCC)-based current-controlled memristor emulator with charge-dependent linear memristance function. Such current-controlled memristors closely model the current ([Formula: see text])–voltage ([Formula: see text]) relationship of the popular TiO2-based physical memristor architecture constructed by Hewlett–Packard (HP). The presented emulator circuit comprises only two grounded passive elements and two external MOS transistors along with a VDCC active element and provides the facility of electronic/resistive tunability. It is found through the detailed literature survey that the presented circuit is the most compact design to realize a charge-controlled memristance simulator as compared to any previously reported structure. The designed configuration has been verified through presented simulation results generated using PSPICE based on 0.18[Formula: see text][Formula: see text]m CMOS technology. It has also been validated through relaxation and chaotic oscillators developed using the proposed VDCC-based memristor emulator and output waveforms have been shown. Furthermore, the discussed memristor emulator has been implemented and verified through commercial ICs, AD844 and LM13700.

A Study on the Variable Inductor Design by Switching the Main Paths and the Coupling Coils

In a radio frequency (RF) system, it is possible to use variable inductors for providing tunable or selective frequency range. Variable inductors can be implemented by the microelectromechanical system (MEMS) process or by using transistors as switches to change the routing of coils or coupling quantities. In this paper, we investigated the design method of a variable inductor by using MOS transistors to switch the main coil paths and the secondary coupled coils. We observed the effects of different metal layers, turn numbers, and layout arrangements for secondary-coupled coils and compared their characteristics on the inductances and quality factors. We implemented two chips in the 0.18 m CMOS process technology for each kind of arrangement for verification. One inductor can achieve inductance values from about 300 pH to 550 pH, and the other is between 300 pH and 575 pH, corresponding to 59.3% and 62.5%, respectively, inductance variation range at 4 GHz frequency. Additionally, their fine step sizes of the switched inductances are from 0.5% to 6% for one design, and 1% to 12.5% for the other. We found that both designs achieved a large inductance tuning range and moderate inductance step sizes with a slight difference behavior on the inductance variation versus frequency.

Starter for Voltage Boost Converter to Harvest Thermoelectric Energy for Body-Worn Sensors

This paper examines the suitability of selected configurations of ultra-low voltage (ULV) oscillators as starters for a voltage boost converter to harvest energy from a thermoelectric generator (TEG). Important properties of particularly promising configurations, suitable for on-chip implementation are compared. On this basis, an improved oscillator with a low startup voltage and a high output voltage swing is proposed. The applicability of n-channel native MOS transistors with negative or near-zero threshold voltage in ULV oscillators is analyzed. The results demonstrate that a near-zero threshold voltage transistor operating in the weak inversion region is most advantageous for the considered application. The obtained results were used as a reference for design of a boost converter starter intended for integration in 180-nm CMOS X-FAB technology. In the selected technology, the most suitable transistor available with a negative threshold voltage was used. Despite using a transistor with a negative threshold voltage, a low startup voltage of 29 mV, a power consumption of 70 µW, and power conversion efficiency of about 1.5% were achieved. A great advantage of the proposed starter is that it eliminates a multistage charge pump necessary to obtain a voltage of sufficient value to supply the boost converter control circuit.