Spiral-Coupled-Line-Based Wilkinson Power Divider.

A spiral-coupled-line-based Ka-band (26.5–40 GHz) CMOS Wilkinson power divider with a shunt capacitor (C) at the input and a shunt RC (or C) between the outputs is reported. The spiral coupled line, i.e., two noninverting spiral transmission lines (TLs) with magnetic coupling, has a positive mutual inductance. This leads to a significant TL-length reduction (from about λ/7 to λ/12) for a specific TL series inductance. At 33 GHz, the power divider achieves prominent S₁₁ of −21.5, S₂₂ of −22.1, S₃₃ of −22.1, S₃₂ of −26.1, S₂₁ of −4.063, and S₃₁ of −4.052 dB. The corresponding amplitude imbalance (AI) and phase difference (PD) are −0.011 dB and −0.336°, respectively. Moreover, S₁₁ is smaller than −10 dB for 0–45.3 GHz, corresponding to 137.3% fractional bandwidth (FBW). S₃₂ is smaller than −10 dB for 24.1–40.2 GHz, covering the Ka-band and corresponding to 48.8% FBW. The power divider occupies a normalized area of 1.2 ×10⁻⁴λ₀², one of the smallest normalized chip areas ever reported for millimeter-wave power dividers. [ABSTRACT FROM AUTHOR]