Single and Four-Element $Ka$-Band Transmit/Receive Phased-Array Silicon RFICs With 5-bit Amplitude and Phase Control

Ka-band SiGe BiCMOS single- and four-element phased arrays capable of both transmit and receive operation with 5-bit phase and amplitude control are presented. The design is based on the All-RF architecture with RF phase shifters and attenuators, and a 4:1 passive power combining/dividing network. The four-element array results in an average gain of ~ 0 dB per channel and a noise figure of 9.0 dB, and is designed to be placed behind III-V T/R modules. The rms phase error is 5.6° (5-bit operation) and < 12.5° (4-bit operation) over a 2 or 5 GHz instantaneous bandwidth, respectively, centered at around 36.5 GHz. In the receive mode, the input P1dB is -16 dBm per channel (IIP3 of - 5.9 dBm), and in the transmit mode, the output P1dB is +4-5 dBm, all at 35-36 GHz. The measured isolation between the channels is better than 30 dB. The array maintained excellent phase characteristics up to 100°C with no change in the rms phase error. Also, ten different four-element phased arrays were tested (40 channels) and result in an rms gain variation of 0.5 dB at 34-39 GHz. The four-element array consumes 171 and 142 mW in the Tx and Rx modes from 1.8 V, and occupies an area of 2.0 × 2.02 mm
²
. To our knowledge, this is the smallest and lowest power consumption on-chip K ¿-band phased-array to-date.