In this paper we present a new integrated CMOS fully-differential buffer. The proposed solution has the peculiarity to avoid external CMFB and show rail-to-rail characteristics, so that it is particularly useful for low-voltage (± 0.75V) applications. Simulation results confirm the theoretical expectations showing, in particular, an excellent internal common mode control.
In this work we present active inductance simulators developed for the control of the mechanical oscillation of a metallic beam. It is possible to reduce the amplitude of these oscillations by subtracting energy to the beam itself. The conversion from mechanical to electrical energy can be done through a piezo-electric sheet connected to the metallic beam. The equivalent circuit is a classical RLC resonating circuit. The required inductance value depends on the oscillating mode that we want to control and can be of hundreds and, in some cases, thousands of Henry (H). A series resistance compensation can help in attenuating the beam vibrations. The solutions proposed in this work allow the implementations of simple circuits, with particular symmetries, which can be also suitable for integrated applications once an integrated CCII is designed. In the literature, circuit implementations performing equivalent inductances are typically based on amplifiers (for example, Antoniou's circuit). Our solutions are based on second generation current conveyors (CCIIs) and allow to obtain both grounded and floating equivalent inductances, of about 1000 H values, working within a regulated frequency range of 3-4 decades.
A temperature control system for integrated resistive gas sensor arrays is proposed. The circuit is a part of a portable system for ambient gas monitoring formed by a sensor array, the IC front-end, the temperature control system with the heater and the pattern recognition algorithm for the processing of the acquired data from the front-end. The sensors are arranged in order to detect a particular kind of gas among which CO2, CH4, H2 and SO2, through a 4-channel read-out front-end able to furnish the digital output signal. The temperature control is simplified by the presence of a second resistance matched with the sensor that operates as a thermal sensor. In this manner it is possible to control the sensor temperature without interference. The problem of the temperature control of the heater is reduced to the control of a resistance. The current (more generally the power) delivered to the heater resistance must be such that the temperature has to remain constant. This task is demanded to the second resistance, close to the heater one, that remains at the same temperature. Typically, such kinds of controls are implemented by topologies that maintain current sources or heater currents constant. In this work, the control circuit is able to maintain the power delivered to the heater resistance as constant.