Millimeter-Wave Tunable Impedance Matching Network in an Advanced CMOS Process

The impedance matching between power amplifier and antenna remains a challenge in millimeter-band front ends, particularly when the antenna impedance varies due to the use of beamforming. This article presents a tunable impedance matching filter fabricated in a 16-nm CMOS process. The frequency of operation is 77GHz, making it suitable for millimeter-wave systems such as radar, Wi-Fi, and mobile communications. The filter is implemented using tunable quarter wavelength transmission lines. A reliability assessment supports that input powers up to 21dBm can be used without risk. The on-wafer measurements demonstrate the functionality of the filter, which can adapt load impedances with a reflection coefficient
$\Gamma $
of up to 0.37 and convert them down to less than 0.20, while keeping the source match also below 0.20 and the loss under 5.5dB. Measurements across the wafer also show low process variability.