A Fully Integrated GaN Dual-Channel Power Amplifier With Crosstalk Suppression for 5G Massive MIMO Transmitters

Abstract

We present a broadband dual-channel power amplifier (PA) with crosstalk suppression for multi-input multioutput (MIMO) communications. Operation of MIMO system with crosstalk is theoretically evaluated for two popular coding schemes including the space-time coding and linear precoding. Design challenges of a multi-channel PA on a single chip are investigated and circuit techniques, including second-harmonic trapping integrated into the output matching network and the use of back-via lines to isolate the channels, are proposed to mitigate the inter-channel crosstalk. A fully integrated dualchannel PA prototype, implemented using a 250-nm GaN-on-SiC process, provides 34.9-36.3 dBm output power, 44-49% poweradded efficiency (PAE), 11.3-12.3 dB power gain, 31.0-34.2 dB second-harmonic rejection, and −28.1 dB to −25.7 dB interchannel crosstalk across 4.5-6.5 GHz. For a 100-MHz 256-QAM signal with 7.2 dB peak-to-average power ratio (PAPR), the PA achieves 29.9 dBm average output power, 30% average PAE, −38.2/−39.1 dBc adjacent channel leakage ratio (ACLR), and −28.2 dB (3.9%) rms error vector magnitude (EVM), without using digital predistortion (DPD). Effect of crosstalk on linearity of the dual-channel PA is also measured and it is shown that for a 256-QAM signal EVM can increase by 3-8 dB, depending on relative power levels of the two channels.

Broadband Performance Assessment of an RF Power Transistor Employing the Real Frequency Technique

“…Step 4 Generation of Foster reactance function: This step is simply performed using the MatLab statement 𝑋𝐹 = 𝑋 − 𝑋𝑚 as in (6).…”

“…OR wireless communication systems, it is essential to design power amplifiers (PA) for variety of applications [1][2][3][4][5][6][7][8]. Nowadays, it is a common practice to employ Gallium Nitrate (𝐺𝑎𝑁) transistors due to their high-power delivering capacity [9][10][11][12][13].…”

Broadband performance assessment of a microwave power transistor employing the real frequency technique

“…It should be clear for the reader that, once the real part 𝑅(𝜔) is represented by the line segments as a continuous function of the angular frequency 𝜔 between two adjacent points, then, the Hilbert transformation (3) is obtained exactly on the given linesegments, specified by (4). Therefore, the pair (4) and (5), for sure define a realizable minimum function 𝐾 𝑚 (𝑗𝜔) = 𝑅(𝜔) + 𝑗𝑋 𝑚 (𝜔) by means of the line segments. In other words, at a given point 𝜔, the value of 𝐾 𝑚 (𝑗𝜔) is exactly determined from its real part 𝑅(𝜔).…”

“…Step 3 Generation of the imaginary part 𝑿 𝒎 (𝝎) of the minimum function: This step is performed using (5).…”

An ultra-broadband power amplifier by using a simple analysis method

“…With the development of communication, the operating bandwidth is becoming larger and larger [1][2][3][4][5]. To design ultra-wideband power amplifiers (PAs) is an interesting research topic.…”