Tunable Notch Filter Based on Carbon Nanotube Transistor

This paper presents a tunable notch filter based on a carbon nanotube (CNT) transistor, highlighting the potential of precisely nanofabricated CNT RF devices for low-voltage frequency control. The filter integrates a high-purity, aligned-array CNT transistor onto a PCB with optimized transmission lines, enabling continuous tuning from 2.3 GHz to 2.5 GHz using control voltages below 1 V. The circuit exhibits strong attenuation exceeding 40 dB across the 2.35–2.45 GHz range, achieving a maximum notch depth of 57 dB and a tuning range of 10 dB. Measured S-parameters closely align with simulation results, confirming the effectiveness of the CNT transistor integration within the notch filter circuit. These results demonstrate the promise of CNT-based tunable filters as compact, low-power solutions for adaptive RF front-ends in next-generation wireless communication systems.