Partial sigma-delta modulated signal and application to power amplifier

With the practical use of the 4G LTE, the need for a versatile power amplifier (PA) increases. The conventional envelope sigma-delta modulation (ESDM) PA is a promising technique for future soft radio, although it has some problems with noise and coding efficiency. This paper describes the application of the technique of single-level ESDM with a thinning out process applied only to the higher part of the envelope and its application to a PA. The effectiveness of this technique for 4G LTE uplink transmissions using conventional 3G PAs is confirmed from the distortion and output power points of view.