Carbon Nanotube CMOS Analog Circuitry

Abstract

Carbon nanotube (CNT) field-effect transistors (CNFETs) promise significant energy efficiency benefits versus today's silicon-based FETs. Yet despite this promise, complementary (CMOS) CNFET analog circuitry has never been experimentally demonstrated. Here we show the first reported demonstration of full CNFET CMOS analog circuits. For characterization, we fabricate analog building block circuits: multiple instances of two-stage op-amps. These CNFET CMOS op-amps achieve gain >700 (maximum derivative of output voltage with respect to differential input voltage), operate at a scaled sub-500 mV supply voltage, achieve high linearity (even when operating at these scaled voltages), and are robust over time (minimal drift over >10 000 cycled measurements over 12 h). Additionally, we demonstrate a front-end analog subsystem that integrates a CNFET-based breath sensor with an analog sensor interface circuit (transimpedance amplifier followed by a voltage follower to convert resistance change of the chemoresistive CNFET sensor into a buffered output voltage). These experimental demonstrations are the first reports of the CNFET CMOS analog functionality that is essential for a future CNT CMOS technology.