High-performance elliptic dual balun for W-band CMOS transceiver

摘要

Two elliptic CMOS dual baluns for W-band (75–110 GHz) transceiver are reported. The input couple-line width of the first dual balun (i.e. dual balun A) is 4 μm. For contrast, the input couple-line width of the second dual balun (i.e. dual balun B) is 2 μm. The width of all the other couple-lines and all space of the two dual baluns is 2 μm. The dual balun can be applied to a power amplifier for four-way equal power dividing. Both the dual baluns occupy a small chip area of 0.0256 mm2. For frequencies of 75～110 GHz, dual balun A achieves S11 of ?10.1～ ?20.2 dB, S21 of ?7.6～ ?9.2 dB, S31 of ?8.5～ ?10.3 dB, S41 of ?7.4～ ?9 dB, S51 of ?9.2～ ?10.4 dB, magnitude of amplitude imbalance (MAI) of 0.42～1.31 dB and phase difference (PD) of 180°～ 186.3° for ports 2～3, and MAI of 0.95～2.4 dB and PD of 175.1°～186.3° for ports 4～5. In addition, dual balun B achieves S11 of ?10.1～ ?18.1 dB, S21 of ?7.8～ ?9 dB, S31 of ?7.8～ ?9.4 dB, S41 of ?7.5～ ?9.5 dB, S51 of ?7.8～ ?9.9 dB, MAI of 0～0.75 dB and PD of 173.4°～180° for ports 2～3, and MAI of 0～0.95 dB and PD of 173.4°～181.3° for ports 4～5, close to those of dual balun A. This means the elliptical dual balun has a large design margin for the input couple-line width. The prominent results of the elliptic dual balun indicate that it is suitable for W-band systems.