A Ku -/ K -Band Switchless Reconfigurable Dual-Band Tri-Mode Filtering CMOS Power Amplifier

In this letter, a fully integrated switchless frequency-reconfigurable dual-band (DB) tri-mode filtering power amplifier (PA) is presented for$Ku$-/$K$-band radar front-end applications. Implemented in 180-nm CMOS technology, the proposed PA operates in low-band (LB), high-band (HB), and DB modes using a switchless dual-core topology to control the signal path without RF switches. A diplexer routes input signals to band-specific filtering input matching networks (FIMNs), which enhance input matching and suppress interband and out-of-band spurious signals. The dual-core driver stage is optimized for LB and HB paths, respectively, and shares a wideband interstage and output matching network (OMN), enabling high output power and efficiency across both bands. The proposed PA achieves lower out-of-band rejection of 67.2/59.9/71.8 dB, upper out-of-band rejection of 50.9/45.7/40.1 dB for LB/HB/DB modes, and interband rejection of 18.7/26.0 dB in LB/HB modes, respectively. Large-signal measurement results show 18.6 dBm$P_{\mathrm {\!\text {sat}}}$and 26.1% PAE at 14 GHz (LB), 17.0 dBm$P_{\mathrm {\!\text {sat}}}$and 13.9% at 22 GHz (HB), and 18.1/16.3 dBm$P_{\mathrm {\!\text {sat}}}$with 18.1%/7.9% PAE at 14/22 GHz (DB). For single carrier 100 MHz 64-QAM signals without digital predistortion (DPD), the measured$P_{\mathrm {\!\text {avg}}}$/ACPR of 12.6dBm/−30.2dBc at 14 GHz (LB) and 11.9 dBm/−31.8 dBc at 22 GHz (HB) are achieved at an EVM level of −25 dB.