A Vertically Integrated Local Oscillator Module for Millimeter-Wave Spectrum Analyzers Using a 10 kHz–100 GHz Interconnect

Traditional planar interconnections in RF front ends limit multilayer integration, resulting in increased module size and high-frequency losses. To address these challenges, this work proposes an ultra-wideband vertical interconnect covering 10 kHz–100 GHz and develops a miniaturized local oscillator driver module for millimeter-wave spectrum analyzers. Measurements demonstrate that the proposed interconnect achieves a return loss better than 10 dB and an insertion loss below 3 dB across the entire frequency range. A K-band interdigital bandpass filter achieves an in-band insertion loss 2.7 dB and out-of-band suppression exceeding 60 dB. Furthermore, a multilayer cavity integrates frequency multipliers, amplifiers, and filters within a compact volume of 23 mm × 20 mm × 20 mm. The proposed approach enables low-loss, high-density integration and provides a practical solution for miniaturized millimeter-wave spectrum-analyzer front ends.