A 24-31GHz Compact Low-Power Complex Impedance Sensor for Beamforming Transmitters in 22nm FD-SOI
 
A 24-31GHz Compact Low-Power Complex Impedance Sensor for Beamforming Transmitters in 22nm FD-SOI ■
 
Xuepu Wu, Xuepu Wu, Xuepu Wu, Yang Zhang, Yang Zhang, Yang Zhang, Giovanni Mangraviti, Giovanni Mangraviti, Giovanni Mangraviti, Rana Yasser ElKashlan, Rana Yasser ElKashlan, Rana Yasser ElKashlan, Dries Peumans, Dries Peumans, Dries Peumans, Piet Wambacq, Piet Wambacq, Piet Wambacq
 
Abstract ■

We present a complex impedance sensor to measure the impedance variations at the output of a (phased-array) transmitter (TX) operating around 28 GHz. Based on complex voltage sensing of the output balun in a transmitter, the envelope detectors and injection-locked ring oscillators (ILRO) split the amplitude and phase sensing of voltages for computing the complex impedance. With a bandwidth spanning from 24 GHz to 31 GHz and an input power dynamic range of 7 dB, this circuit can sense reflection coefficients up to 0.74 with a maximum magnitude error of 0.14 and a maximum phase error of 12.8°. It consumes 8 mW of power and occupies only 0.0043