In this paper, novel carbon nanotube (CNT) based operational transconductance amplifiers (OTAs) have been designed and simulated. Three types of CNT-based OTAs have been designed at 45 nm technology node and have been compared with the conventional CMOS-based OTA. The comparative analysis of the key characteristics of all the devices has revealed that a significant improvement in performance is observed in the CNT-based OTAs, particularly in a pure CNT-OTA. In the pure CNT-OTA, DC gain has increased by 218%, slew rate has increased by 22.58%, the output resistance has increased by 55.2% and the power consumption is ∼ 193 times less in comparison to the conventional CMOS-OTA. Further, common mode rejection ratio (CMRR) and power supply rejection ratio positive (PSRR+) has increased by 31.87% and 136.3%, respectively in pure CNT-OTA. The performance of CNT-based OTAs has also been studied thoroughly by varying the number of CNTs (N), CNT pitch (S) and the diameter of CNTs (D CNT ) at 0.9 V. It has been observed that their performance can be improved further by using optimized values of CNT number; inter CNT-pitch and diameter. The stability analysis has shown that the pure CNT-OTA is highly stable. A 16.7% and 4% increase in phase and gain margins is achieved in the pure CNT-OTA in comparison to the bulk CMOS OTA. Finally, band and high pass filters have been realized by using the proposed CNT-based OTAs.
In this paper, we present a new structure of lateral bipolar transistor on selective buried oxide. The device does not use highly doped regions; however, it employs the concept of creating n and p type charge plasma in undoped silicon by using metal electrodes of different work functions. The proposed device is named as the selective buried oxide based bipolar charge plasma transistor (SELBOX-BCPT). An extensive 2D simulation study has revealed that the proposed SELBOX-BCPT device not only possesses all the advantages of the conventional BCPT device, but it also addresses various severe problems of the BCPT device. A significant improvement in major issues of poor cutoff frequency ( f T ), low breakdown voltage and thermal efficiency has been achieved. It has been observed that the f T has increased by ∼94.6%, the breakdown voltage by 23.47% and the device is much cooler than the conventional BCPT device. A large current gain is obtained in the proposed device and is on a par with the conventional BCPT device. Further, by using mixed-mode simulation feature of the Atlas simulator, inverting amplifiers based on SELBOX-BCPT and the conventional BCPT have been realized. A significant improvement of 15% in switching-on transient time and 25.8% in switching-off transient time has been achieved in the proposed device in comparison to the conventional BCPT device.
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