Double-Gate MOSFET Technology for OFDM RF Power Amplifier Design

Power Amplifiers (PA) nonlinearities affect drastically the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems. It requires very linear transmission because of high peak to average power ratio (PAPR).

It is thus important that the intrinsic PA linearity be made as high as possible. In our design, it is shown that the gate-source capacitance of a MOSFET device is a major source of nonlinearity that can limit the performance of a CMOS class-AB power amplifier, so the DG-SOI MOSFET which improves the gate-source capacitance, and increase linearity of RF PA, and decreases PAPR problem.

Performance, tunability and efficiency of double gate MOSFET (DG-MOSFET) based PA are investigated.  Specifically, we propose a RF PA topologies with 0.13 um DG-CMOSFET technology and study its performance via computer simulations with cadence. The PA is a two stage amplifier the driver stage is two common-source connected transistors act as a differential pair and an active load formed by  the  current  mirror  generates  the  single-ended  the output stage is cascode configuration .Important design considerations include output power ,compression point and linearity. The amplifier has a 1dB compression point of 16 dBm (output referred) and 5.2 dBm (input referred).For power gain, a 12.7 dB value is achieved.

We also provide a comparison of the simulated performance figures of merit for the DG-MOSFET amplifiers with those reported for the conventional bulk CMOS based PAs with the same design, which shows that proposed designs are either comparable or better than the standard CMOS counterparts in all figures of merits considered.