Single EXCCII based square/triangular wave generator for capacitive sensor interfacing and brief review

Abstract

Square/triangular wave generators are very important building blocks and find wide applications in resistive/capacitive sensor interfaces, pulse width modulation (PWM), analogue to digital convertor and so on. A variety of generator circuits have been reported in the literature so far. This chapter gives a brief review of existing generator circuits. To further enrich the area, this chapter proposes a novel square/triangular wave generator circuit, which is realised using single extra-X second generation current conveyor (EXCCII), four resistors and one grounded capacitor. The circuit provides both square wave and triangular wave in voltage-mode simultaneously. The circuit can operate at the frequency as low as 100 mHz and is capable of providing a wide sweep range of frequency of six decades (100 mHz to 310 kHz). The proposed generator can precisely detect the capacitor variations up to six decades in the range of 100 pF to 100 mF. Therefore, the proposed circuit finds suitable application as capacitive sensor interface with low-voltage and low-power characteristics. The effects of nonidealities and parasitic of EXCCII along with the effects of temperature variations on the proposed generator circuit are studied. The possible aspect of adjusting the duty cycle of output waveforms via DC current source is also shown. The theoretical proposal has been verified by SPICE simulations.