A 23-41 GHz Broadband Power Amplifier With Common-Mode Stability Enhancement Technique in 65-nm CMOS Process

Here, we present a millimeter-wave (mm-Wave) broadband power amplifier (PA) with a common-mode (CM) stability improvement technique. Unlike conventional broadband PAs, which consider only the differential-mode (DM) stability, our proposed PA simultaneously enhances the DM stability and the CM stability. To ensure CM stability, a small resistor is first connected in series to a capacitor to reduce its Q factor; then, these components are attached in parallel at the center tap of the input balun to increase the CM path loss. Therefore, the stabilization of the PA can be improved over the entire frequency band to ensure a properly broadband work. Our proposed broadband PA with CM stability enhancement technique is finished in a commercial 65 nm CMOS process with a core area of 0.13 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. Adopting continuous-wave testing, the PA exhibits 56.3% 1-dB output 1-dB compression point power (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OP</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1<i>dB</i></sub>) fractional bandwidth and 3-dB small signal gain fractional bandwidth from 23 to 41 GHz that covers the whole Ka-band. At 28/39 GHz, the PA provides +14.8-/+14.1-dBm saturation output power (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>sat</i></sub>), +12.4-/+12.0-dBm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OP</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1<i>dB</i></sub> and 29.8%/23.8% peak power added efficiency (PAE). The measured stability parameters indicate the proposed CM stability enhanced broadband PA is unconditionally stable over the entire frequency band. For a 100-MHz 1-CC 64-QAM signals (roll-off factor = 0.45 and PAPR = 7.1 dB), at a carrier frequency of 28 GHz, the PA demonstrates 8.6 dBm average output power (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>avg</i></sub>), 5% average power added efficiency (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PAE</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>avg</i></sub>), -32.4 dBc adjacent channel leakage ratio (ACLR) and -25.4 dB EVM. For a 400-MHz single-carrier 64-QAM signal, this proposed PA still provides 8.1-dBm <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>avg</i></sub> and 4.5% <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PAE</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>avg</i></sub> with a -34.2 dBc ACLR and -25.3 dB rms EVM at 28 GHz.