Envelope tracking of a radio frequency amplifier for Long Term Evolution using a three-level class-G modulator

[摘要] In this contribution, efficiency enhancement of a radio frequency (RF) poweramplifier (PA) for Long Term Evolution (LTE) base stations using envelopetracking is investigated. The dynamically adapted drain bias voltage isprovided by a three-level class-G modulator. The potential of this biasmodulator is demonstrated with a class AB PA built in gallium nitride (GaN)technology with an operation frequency of 2.75 GHz, a maximumoutput power of 41 dBm and a peak power-added efficiency (PAE) of60%. When driven by an LTE signal with a bandwidth of20 MHz, overall system efficiency can be increased from 17%with a constant supply voltage up to 29% with envelope tracking. This isaccompanied by a reduction of linearity. Adjacent channel leakage ratio(ACLR) decreases by 10 dB in the first and by 18 dBin the second adjacent channel, respectively. Error vector magnitude (EVM)increases from 9% up to 29%.

[学科分类] 电子、光学、磁材料