Design and Implementation of a High-Performance CMOS Dual Balun for Millimeter-Wave Star Mixer and Four-Way Power Amplifier

A planar miniature CMOS dual balun with unequal coupled-line width for millimeter-wave (MMW) transceiver is reported. The dual balun can be applied to a star mixer or a four-way power amplifier for four-way equal power dividing. The dual balun occupies a small chip area of 0.0252 mm(2) and achieves S-11 smaller than -12 dB for frequencies of 50 similar to 110 GHz. For frequencies of 55-65 GHz, the dual balun achieves S-21 of -7.6 similar to-7.9 dB, S-31 of -7.9 similar to-9 dB, S-41 of -7.5 similar to-7.9 dB, S-51 of -7.8 similar to-8.9 dB, magnitude of amplitude imbalance (MAI) of 0.34 similar to 1.1 dB and phase difference (PD) of 179.22 degrees similar to 180.78 degrees for ports 2 similar to 3, and MAI of 0.3 similar to 1 dB and PD of 178.83 degrees similar to 180.48 degrees for ports 4 similar to 5. For frequencies of 75 similar to 85 GHz, the dual balun achieves S-21 of -9.1 similar to-10.5 dB, S-31 of -10.7 similar to-12.7 dB, S-41 of -9.1 similar to-10.5 dB, S-51 of -10.7 similar to-12.6 dB, MAI of 1.7 similar to 2.2 dB and PD of 179.42 degrees similar to 180.59 degrees for ports 2 similar to 3, and MAI of 1.6 similar to 2.1 dB and PD of 179.93 degrees similar to 180.73 degrees for ports 4 similar to 5. The state-of-the-art results of the proposed dual balun indicate that it is suitable for 60 GHz and 77 GHz communication systems.