Enhancement of Closed-Loop Gain of Organic Amplifiers Using Double-Gate Structures

We demonstrate a significant improvement in the gain of closed-loop organic amplifiers by systematically controlling the threshold voltage (VTH) with double-gate structures. The use of an ultrathin parylene dielectric results in an operating voltage as low as 4 V with a supply voltage (V
_DD
) of 2 V. Double-gate structures were introduced for controlling VTH of the transistor and the switching voltage of the inverter. The maximum dc gain of the inverter was recorded as 29.3 dB at a V
_DD
value of 2 V. In addition, the switching voltage of the circuits can be controlled from 0 V to V
_DD
without a significant performance degradation. The effects of the VTH control on the closed-loop amplifier were systematically investigated and a significant gain improvement of up to 18.8 dB was demonstrated in the closed-loop gain by adjusting the switching voltage to half of V
_DD
.