tunable vhf transconductor using double-gate carbon nanotube field effect transistors (dg-cntfets) and its application in gm-c filters

This paper presents a new tunable operational transconductance amplifier (ota) based on double-gate carbon nanotube field effect transistor (dg-cntfet). the inverter-based ota works with low supply voltage (1.0 v) and it is suitable for continuous-time filters in the vhf range. the tunability of this ota is easily achieved by the control voltages of the dg-cntfet’s back gates. the proposed ota has no internal nodes and allows rail-to-rail input voltage swing. based on the results of hspice simulations in the 32 nm process, the ota has a dc gain of 81 db. unity gain frequency (ugf) of the proposed ota is 1.12 ghz and its phase margin is 90°. as a sample application, a second-order filter with low-pass and band-pass outputs was implemented based on the proposed ota. based on the simulation results, the dg-cntfet-based filter can provide a frequency range of 68 khz to 143 mhz with a tuning range greater than 160 times for low-pass response. the power consumption of the filter in the tuning range can vary from 0.17 μw to 9.7 mw depending on the required filtering range.