An adaptive digital processor for power efficiency enhancement in hybrid supply modulators. (2nd April 2015)

• Record Type: Journal Article
• Authors: Salimi, Atefeh; Dehghani, Rasoul; Nabavi, Abdolreza
• Is Part Of: International journal of circuit theory and applications. Volume 44:Number 2(2016:Feb.)
• Page Start: 428
• Page End: 443
• Publication Date: 2015-04-02
• Subjects: digital processor -- CMOS -- envelope modulators -- envelope tracking (ET) -- power amplifier (PA); Electric circuit analysis -- Periodicals; 621.319205
• DOI: 10.1002/cta.2085
• Languages: English
• ISSNs: 0098-9886

Abstract

Summary: A novel digital envelope modulator for envelope tracking radio frequency power amplifier is presented in this paper. The proposed modulator consists of a parallel combination of linear class AB and switching class D power amplifiers that are controlled digitally. In the previous analog architectures, the requirements needed for the AB operational amplifier such as high‐current driving capability, high bandwidth and large output swing is usually obtainable at high overall static power dissipation. The digitally controlled power opamp presented here not only provides the aforementioned requirements but also reduces power dissipation compared with previous work. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog parallel hybrid envelope modulators. The digital processor of the modulator is evaluated with a 45‐nm complementary metal oxide semiconductor technology. The overall power consumption of the digital processor is around 142 mW at 1.5‐GHz clock frequency. As an application, the designed digital class AB is incorporated in a complete envelope modulator architecture. The overall efficiency of the modulator, including the digital processor power consumption, is around 82% at an average 32 dBm output power for a 5‐MHz input signal. Copyright © 2015 John Wiley & Sons, Ltd. Abstract : In this paper, a novel digital supply modulator is presented. The proposed modulator consists of a parallel combination of class AB and class D power amplifiers that are controlled digitally. The proposed amplifier has high‐current diving capability, high bandwidth and large output swings, while it consumes a lower overall static power compared with analog hybrid architectures. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog hybrid modulators.