Broadband and Low-Loss 1 : 9 Transmission-Line Transformer in 0.18- CMOS Process

摘要

This letter proposes a transmission-line transformer (TLT) with high impedance-transformation ratio of 1 : 9 for wideband power amplifier design. The 1 : 9 TLT is realized with broadside-coupled and multiple-metal stacked transmission lines and achieves a broadband impedance transformation from $hbox{5.0} pm hbox{0.1} Omega$ optimal load impedance of the power cell to 50-$Omega$ load with a bandwidth of 4.4 to 6.6 GHz, which covers the required bandwidth of the IEEE 802.11a WLAN application. The measured minimum insertion loss is 1.07 dB at 5.8 GHz with a 3-dB bandwidth of 164%. This 1 : 9 TLT is fabricated in standard 0.18-$muhbox{m}$ CMOS process with a chip area of $hbox{426} muhbox{m} times hbox{589} muhbox{m}$ including the test pad.