A CCII-based wide frequency range square waveform generator

In this paper, we propose a novel current-mode solution suitable for the square waveform generation. The designed oscillator, which utilizes only two positive second-generation current conveyors as active blocks, six resistors and a capacitor, is based on a current differentiation, instead of voltage integration, typical of developed solutions both in voltage-mode and in current-mode approaches, so avoiding circuit limitations due to the node saturation effects. The proposed circuit has been designed, as an integrated solution at transistor level, in a standard CMOS technology, with low-voltage (+/- 1V) and low-power (430 mu W) characteristics. Simulation results have confirmed the good circuit behaviour, also for working temperature drifts, showing good linearity in a wide oscillation frequency range, which can be independently adjusted through either capacitive (in the range pF-mu F) or resistive (in the range M Omega-G Omega) external passive components. Waiting for the chip fabrication, preliminary measurements have been performed using a laboratory breadboard employing the CCII with AD844 commercial component and sample capacitors and resistors. The experimental results have shown good agreement with both simulations and theoretical expectations. Copyright (C) 2011 John Wiley & Sons, Ltd.