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 1ow-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 S11 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$\sim$0.5 dB. The input IP3 for the rest of the receiver chain is about -27dBm.