A 5.8 GHz Four-Channel RF Beamforming IC Based on a Vector Modulator for Wireless Power Transmission

A 5.8GHz four-channel transmitter RF beamforming IC based on a vector modulator fabricated via the 130 nm RF CMOS process is presented here. The vector modulator controls the gain and phase independently by steering the tail current sources of a Gilbert-cell-based vector synthesizer. It offers 8-bit phase control for 360° and 4-bit gain control for a 20 dB dynamic range, with the size not depending on the control bits. A four-way differential RF power divider is introduced to implement the four-channel IC, in which off-chip ground bonding inductance is resonated out through the introduction of additional capacitances to a
$\lambda /4$
impedance transformer of a four-way Wilkinson divider to reduce the insertion losses and errors. The measured total RMS gain error of the vector modulator is 0.312 dB and the total RMS phase error is 0.329°. It shows 20 mW DC power consumption per channel, 5.19 dBm OP1dB, and a 3 dB gain overall including 6 dB of dividing loss.