Highly Efficient 3-Bit Digital Power Amplifier for OFDM Waveform Amplification

In this work, we present a digital power amplifier (DPA) and signal-optimized control technique suitable for the amplification of orthogonal frequency division multiplexing (OFDM). OFDM is high peak-to-average ratio (PAPR) signal that naturally arising from spectrum efficiency modulations. A 3-bit DPA implemented with three power-scaled transistors which are turned on off based amplitude, while phase modulation restored using radio (RF) input signal. The unavoidable nonlinearities at output due to PA switching minimized by accounting probability density function (pdf). This pdf priori knowledge design an optimal quantizer minimizes distortion distributing levels where amplitude more similar original one. Back-off within $2^{3}=8$ possible states then optimized implementing load-modulating combiner. Theory example combiner network provided demonstrated DPA. reported prototype operates 1.5 GHz achieves maximum power-added (PAE) 64.3% maintains drain greater than 47% over range 36.6 45.2 dBm (8.6-dB range).