High efficiency power amplifier based on envelope elimination and restoration technique

Abstract

-Due to complex envelope and phase modulation employed in modern transmitters it is necessary to use power amplifiers that have high linearity. Linear power amplifiers (classes A, B and AB) are commonly used, but they suffer from low efficiency especially if the transmitted signal has high peak to average power ratio (PAPR). Kahn's technique based on envelope elimination and restoration (EER) is based on idea that high efficiency power supply (envelope amplifier) could be used to modulate the envelope of high efficient non linear power amplifiers (classes D or E). This paper presents solutions for power amplifier that performs envelope modulation and class E amplifier that is used as a non linear amplifier. The envelope amplifier is implemented as a multilevel converter in series with linear regulator and can provide up to 100 W of instantaneous power and reproduce 2 MHz sine wave. The implemented Class E amplifier can operate at 120 MHz with efficiency near to 85%. The envelope amplifier and class E amplifier have been integrated and efficiency and linearity of the implemented transmitter has been measured and presented.

Survey of architectures and optimizations for wide bandwidth envelope amplifier

“…These circuits have been used for an EER amplifier and this envelope amplifier provides 100W peak power with 2MHz bandwidth [27] Moreover, they also may work well in an ET configuration by removing the linear regulator.…”

“…Including a parallel linear regulator (group A.2) makes easier to achieve a high bandwidth [15,16]. The solution that presents a good trade-off between power and bandwidth is the one based on the multilevel with series regulator [23][24][25][26][27]0 (group D).…”

A new design approach of high efficiency S-band 25 W mixerless power modulator based on high voltage 50V GaN-HEMT technology

“…Several techniques have been implemented over the past few decades to efficiently amplify high PAPR signals such as Doherty [2], Envelope Elimination and Restoration (EER) [3] and Envelope Tracking [4] to improve the efficiency at backoff levels.…”

Analysis of Intermodulation Distortion in OFDM Based Transmitter Using EER Technique

“…The EER transmitter architecture is attractive not only for high PAPR narrowband communication systems but also for wideband systems [10], [11]. Increasing envelope amplifier bandwidth, however, means increasing the negative influence of switching characteristics of power transistors on the total distortion of the power amplifier.…”