Single-Ended and Differential Ka-Band BiCMOS Phased Array Front-Ends

Single-ended and differential phased array front-ends are developed for Ka-band applications using a 0.12 mum SiGe BiCMOS process. The phase shifters are based on CMOS switched delay networks and have 22.5deg phase resolution and <4deg rms phase error at 35 GHz, and can handle +10 dBm of RF power (P_1dB) with a 3rd order intermodulation intercept point (IIP3) of +21 dBm. For the single-ended design, a SiGe low noise amplifier is placed before the CMOS phase shifter, and the LNA/phase shifter results in 11 plusmn 1.5 dB gain and <3.4 dB of noise figure (NF), for a total power consumption of only 11 mW. For the differential front-end, a variable gain LNA is also developed and shows 9-20 dB gain and <1deg rms phase imbalance between the eight different gain states. The differential variable gain LNA/phase shifter consumes 33 mW, and results in 10 + 1.3 dB gain and 3.8 dB of NF. The gain variation is reduced to 9.1 plusmn 0.45 dB with the variable gain function applied. The single-ended and differential front-ends occupy a small chip area, with a size of 350 times 800 mum² and 350 times 950 mum2, respectively, excluding pads. These chips are competitive with GaAs and InP designs, and are building blocks for low-cost millimeter-wave phased array front-ends based on silicon technology.