A CCII-Based Multi-Waveform Generator for Configurable Sensor Excitation

Configurable excitation and modulation signals are required in many sensor interface systems, including capacitive, MEMS, impedance-based, and embedded mixed-signal platforms. In this context, the proposed work presents a multi-stage current-mode waveform generator based on Second-Generation Current Conveyors (CCIIs), designed as a compact and reconfigurable analog building block for sensor excitation and signal-conditioning applications. The architecture combines cascaded CCII-based functional stages, including a comparator and two current-mode integrators, enabling the generation of square, triangular, quasi-sinusoidal, and pulse-width-modulated waveforms through a compact structure. The proposed solution is validated through an AD844-based discrete implementation, used as a proof-of-concept to assess the feasibility of the current-mode architecture and its suitability for sensor-oriented signal generation. The circuit provides multiple synchronized waveform outputs that can support different sensing tasks: sinusoidal signals for AC excitation and impedance-based measurements, triangular waveforms for ramp-based capacitive sensing schemes, square waves for timing and switching operations, and PWM signals for duty-cycle-based readout or modulation. Simulation results confirm correct multi-waveform generation over an operating frequency range from 80 kHz to 500 kHz. The generated waveforms preserve the expected square-to-triangular-to-sinusoidal transformation produced by the cascaded current-mode stages, while PWM operation is obtained through threshold-based comparison. The effect of practical non-idealities is also observed at higher frequencies, where amplitude attenuation and distortion increase due to finite bandwidth and inter-stage loading. Simulation and experimental results have demonstrated that the proposed generator can be used as a versatile signal-generation core for compact sensor interfaces. Future work will address a fully integrated CMOS implementation and validation within a capacitive sensor excitation and PWM-based readout framework.