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Low complexity charge pump envelope tracking RF power amplifier

A low complexity envelope tracking (ET) RF power amplifier (PA) is described intended for handsets and applications where a large number of PAs are needed in a small space. An analogue charge pump structure is used to increase the supply voltage to an RF amplifier during the peaks of a high peak-to-average power ratio (PAPR) signal. Combined with an RF amplifier based on a LDMOS transistor, 42.9% efficiency can be achieved at 31.3 dBm output power (POUT) when amplifying a 5 MHz bandwidth 3GPP Long Term Evolution (LTE) signal with 8 dB PAPR. The first channel adjacent power ratio (ACPR) was -30.4 dB, meeting the 3GPP handset emission mask without the need for digital pre-distortion (DPD). High efficiency and linearity can be achieved over a large POUT range by disabling ET operation at 3.7 dB back-off.