Digitally-compatible ring oscillator frequency driven tuning of CN-TFT amplifiers: Performance compensation under statistical and morphological variations

Carbon Nanotube network based Thin-Film Transistors (CN-TFTs) are excellent candidates for next generation flexible electronics applications. However CN-TFT circuits suffer from imperfections due to morphological variations of fabricated carbon nanotube geometries that cause wide performance variations in analog amplifiers built from these CN-TFTs. Improved fabrication methods and sophisticated process control techniques are not sufficient for tackling these imperfections. In this paper, a new digitally-compatible tuning method is proposed for CN-TFT based amplifier designs. The amplifier is placed in a ring-oscillator configuration using two additional digital inverters, appropriately modified to allow oscillation of the inverter-inverting amplifier-inverter configuration. The frequency of oscillation is then used to drive a tuning algorithm that recovers the performance of the amplifier under statistical and morphological fabrication process variations. The method is very easy to implement and simulation studies show excellent results.