D-Band RX Front-End With a 0 $^{\circ}$ –360 $^{\circ}$ Phase Shifter Based on Programmable Passive Networks in SiGe-BiCMOS

Active phased arrays are key enablers for high-capacity wireless links and imaging sensors at millimeter wave, but require advanced front-end circuits. On the receiver side, the front-end comprises a low-noise amplifier (LNA) followed by a programmable phase shifter (PS), required to adjust the phase of each channel before performing the coherent summation of the signals captured by different antenna elements. In D-band, conventional PSs based on the vector interpolation principle limit the dynamic range with a noise or linearity penalty due to transistors operating close to $f$ max, in currently available silicon technologies. This work presents a front-end where the variable phase shift is achieved using passive structures, with a noise figure equal to the insertion loss (IL) but inherently linear. Different passive networks providing a programmable phase shift in fine and coarse steps are developed and interleaved with active gain stages to build a 0 $^{\circ}$ –360 $^{\circ}$ PS. Cascode structures are used as gain stages, in the PS and in the preceding LNA, and reactive feedback is introduced around the common-emitter (CE) device to boost the gain. A D-band receiver front-end is implemented in BiCMOS 55-nm technology. With a power consumption of 80 mW from a 2 V supply, measurements prove 20 dB average gain, 130–170 GHz operating frequency with 0 $^{\circ}$ –360 $^{\circ}$ phase shift control, and average NF and $\mathrm{OP_{\rm 1\,dB}}$ of 7 dB and $-$ 2 dBm, respectively. Normalizing the dynamic range to power consumption, the achieved results compare favorably against state-of-the-art.