Frequency Reconfigurable Pole-Zero Inversion Image Rejection Filter for 5G FR2 Transceivers

A frequency reconfigurable image rejection filter (IRF) for 5G FR2 bands (24.25–27.5 GHz and 37–40 GHz) transceivers is presented. The circuit adopts a novel pole-zero inversion (PZI) topology and constructs two operating modes, high-pass (HP) mode and low-pass (LP) mode. PZI means the poles of one mode are the zeros of the other mode, and it is realized by two types (series-parallel, thru-ground) of resonators with reconfigurable poles and zeros. The PZI IRF is fabricated using a 65-nm CMOS process and the core size of it is 0.0315 mm2. It achieves the minimum loss of 5.4/5.7 dB and maximum image rejection ratio (IRR) of 24.5–26.5 dB with 6 GHz intermediate frequency (IF) frequency in two modes, respectively. To the best of the authors’ knowledge, this is the first reconfigurable IRF in millimeter-wave frequencies. This design provides a high IRR solution for single-path non-IQ 5G FR2 frequency reconfigurable transceivers.