Among potential candidates to replace the CMOS transistor channel, several materials such as CNTs, GNRs, and SiNW show an interesting behavior known as “Ambipolarity.” Ambipolarity, means that n- and p-type behavior can be observed in the same device. By adding a fourth terminal to control the ambipolarity, a new category of devices has seen the light under the name of Ambipolar Independent Double Gate FETs “Am-IDGFETs.” These devices are capable of operating as either n-type or p-type switches according to their back-gate bias voltage. As a result, more options are available with no counterparts in CMOS technology. Based on Am-IDGFETs, we propose a circuit design approach to achieve compact logic structures by merging every two transistors in series structure using the in-field controllability via the back-gate of ambipolar devices. The approach is demonstrated for two logic styles: with a complementary static logic design style, it demonstrates an efficiency that can improve the compactness of logic structure by a factor of 2x, while with a dynamic logic style, a gain of 30% in terms of transistors count is achieved for a variety of application scenarios. We evaluate the performances of circuits designed from this approach in a case study focused on double gate carbon nanotube FET technology. Simulations results show that, with respect to conventional CMOS-16 nm gates and for comparable power consumption, time delay and integration density can both be improved by a factor of 2x and 2.5x, respectively. The power-delay-product is improved by 30%.