DSP-based technique for power efficiency improvement in low-IF 5 GHz WLAN transmitter

This paper proposes a DSP based technique for power efficiency enhancement in a low-IF WLAN IEEE 802.11a transmitter architecture. This work combines a clipping function with an oversampling operation for reducing signal envelope variation. For that, an optimal oversampling factor was firstly chosen for a given input signal type. A clipped signal is then applied to a predistortion-based linearized power amplifier. The value of the clipping ratio is set so that the resulting overall transmitter error vector magnitude (EVM) meets the standard specifications. This allowed an important reduction of the power back-off that in its turn leads to a significant increase of the power added efficiency (PAE). Experiments that were performed using a 1-watt commercial solid state power amplifier demonstrated a relative power efficiency improvement of about 80 %.