Low Noise IQ Generation Employed in an Active Vector Modulator for 5G Ka-Band Beam Forming Transceivers

This paper investigates a compact, low noise differential in-phase (I) and quadrature signal (Q) generator. The proposed circuit utilizes a pair of mutual inductors to generate 90° phase shift which results in the same voltage gain for both I and Q paths. while it is in contrast with an RC-CR structure where the same gain for IQ paths cannot be achieved with a proper 90° phase shift simultaneously. The simulation results in a 130 nm SiGe-BiCMOS technology, indicate that a 3-dB bandwidth of 1.54 GHz around 28 GHz center frequency is achieved. Employing the proposed structure in a low-IF receiver as part of the phase-shifting block has indicated a voltage gain of 30 dB for the desired signal while 40 dB rejection is provided at 22.275 GHz for the image signal. NF and S
₁₁
are less than 3.5 dB and -17dB, respectively, for the entire band of interest while the receiver consumes 8 mA from a 2V power supply. The phase error is less than 5° and the gain variation error is 0.3~0.5 dB. The input IP3 for the rest of the receiver chain is about -27dBm.