Advanced envelope delta-sigma transmitter architecture with PLM power amplifier for multi-standard applications

This paper presents a new modified envelope delta-sigma (DS) based transmitter architecture with good linearity and efficiency performance without applying any linearization techniques. For the proposed transmitter setup, a pulsed load modulation (PLM) amplifier is implemented and used for its high power efficiency at the back-off power levels. For high efficiency performance of the PA and maintaining the linearity of the system, an envelope DS modulator is utilized to quantized standard signals prior to the PA. Simulation results also show that higher coding efficiency of the quantized signal is achievable employing the envelope DS modulator instead of its Cartesian DS modulator counterpart. To validate the proposed technique, a transmitter prototype is implemented and tested with standard signals with various pick-to-average power ratios (PAPRs). Using this transmitter setup for a 3MHz bandwidth LTE signal with 7dB PAPR and a WiMAX signal with 1.25MHz bandwidth and 7.9dB PAPR, the average drain efficiency of about 45% and 44% are obtained, respectively, at the average output powers of 24.8dBm and 25.7dBm.