Abstract
In this article, we propose a broadband fully integrated power amplifier (PA) using a waveform shaping harmonic matching network. A comprehensive theory is developed for the proposed multi-resonance harmonic matching network to derive design criteria for achieving wide bandwidth, low insertion loss, and optimum load impedances in the second- and third-harmonic frequency bands. Furthermore, it is shown that this network can be realized using a lower total inductance compared to a standard bandpass network which is an important feature in reducing chip area and fabrication cost. A fully integrated PA prototype is implemented using a 250-nm GaN-on-SiC process with 28-V supply. The PA provides 33.9–36.1dBm output power (at 2–3dB gain compression), 42–51% drain efficiency (DE), 38–48% power-added efficiency (PAE), and 10–12.2dB power gain, across 4.0–6.0GHz. The output-power 1-dB bandwidth is 3.6–5.6GHz (44.5%). For a 64-QAM signal with 8dB peak-to-average power ratio (PAPR) at 5.0GHz, the PA can provide 30.2dBm average output power and 32% average PAE with RMS error vector magnitude (EVM) of −34.0/−32.4/−28.4dB (2.0/2.4/3.8%) for 50/100/200MHz modulation bandwidth, without using digital predistortion (DPD). The maximum average output power and average PAE, under the linearity constraint EVM <−28dB, are respectively 32.1/32.0/30.2dBm and 39/38/32%, for modulation bandwidth of 50/100/200 MHz.
Highlights
INTRODUCTIONB ROADBAND power amplifiers (PAs) are essential components for multi-band fifth generation (5G) wireless
B ROADBAND power amplifiers (PAs) are essential components for multi-band fifth generation (5G) wirelessManuscript received March 6, 2021; revised June 1, 2021; accepted July 5, 2021
The chip backside is attached to the test PCB using a conductive epoxy, while its RF and bias pads are wire-bonded to the board
Summary
B ROADBAND power amplifiers (PAs) are essential components for multi-band fifth generation (5G) wireless. A complicated circuit must usually be used as the load modulation network, but its unavoidable parasitic capacitive and resistive elements can limit the bandwidth and degrade the overall efficiency of the PA These issues can overshadow the PA back-off efficiency enhancement advantage. A broadband design approach for the output matching network, which can achieve wide bandwidth, low insertion loss, and optimal load impedances in the fundamental and harmonic frequency bands, can be very useful for such PAs. In this article, we further develop the preliminary concepts introduced in [22]. The PA circuit design details using the harmonic matching network are described, where design considerations to achieve high efficiency and linearity over a wide bandwidth are elaborated.
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