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A novel and compact millimeter-wave (mm-Wave) spatial power combiner is developed integrating a silicon-based integrated circuit (IC) in a metal waveguide (WG). As an initial step toward integrating a silicon-based active IC in a WG, a passive back-to-back (B2B) transition incorporating a four-way spatial power splitter and combiner is realized at $E$ -band (71–86 GHz). In contrast to existing solutions, the proposed design considers power splitting and combining using a low-loss wireless transition between the IC and the WG. The proposed B2B structure comprises an IC implemented using the Institute for High Performance Microelectronics (IHP’s) 0.13- $\mu \text{m}$ SiGe BiCMOS technology integrated into the $H$ -plane of a WG. The IC is postprocessed and assembled in the WG prototype. The measured prototype shows a return loss better than 13 dB, an average insertion loss of 1.7 dB for a single transition, and a fractional bandwidth of 26.4% (69–90 GHz).

This paper studies the power combiner efficiency of multiple Power Amplifier (PA) output signals that are combined within a low-loss contactless transition, intrinsically having low isolation characteristics. Since the PA performance is sensitive to load impedance variations, poor isolation may affect each PA performance, thereby reducing the overall power combiner efficiency. Load impedance variations can e.g. be due to process, supply-voltage and temperature variations. A four-way spatial power combiner (SPC) design is compared to an on-chip Wilkinson Power Combiner (WPC) implemented in 0.13 µm SiGe BiCMOS technology incorporating a 50 Ω impedance matching net-work. The WPC occupies 84% more area than the non-isolating SPC. Moreover, the non-isolating SPC has an average efficiency 14% larger than the WPC. For physically realistic variations, simulated results show a σ-variation of 2.81 mW in P out and 0.87 % in PAE for the non-isolating SPC, and 2.34 mW in P out and 0.45 % in PAE for the WPC (@1 dB compression).

A novel contactless transition from a (Bi)CMOS Silicon IC (p-doped substrate) to a metal waveguide in E-Band is presented. This transition also incorporates a spatial power combiner in air to enable direct electromagnetic coupling from an array of on-chip microstrip transmission lines to a single waveguide mode, and vice versa. The transition is relatively low loss and is particularly suitable for high-power mm-wave applications. The simulated return loss of a four-channel passive back-to-back transition is better than 10 dB over the frequency band ranging from 60–90 GHz (E-Band). The average insertion loss of a single transition is 1.31 dB over the entire E-Band.

A low noise amplifier (LNA) realized in CMOS technology operating in the 60 GHz band has been packaged in gap-waveguide technology. The bare die LNA is implemented in 40 nm digital CMOS technology. The chip interface is wire-bonded to a PCB employing a contactless connection to a metal waveguide. The co-simulation results of the back-to-back combined LNA-waveguide structure features a system available gain of 10.5 dB and a noise figure NF of 4.63 dB, which is comparable to the isolated LNA performance (12.8 dB available gain, 3.95 dB NF).

A passive W-band 19-channel spatial power splitter/combiner is presented, for the applications in grid amplifiers design. The design employs a linear array of chip-to-air-filled waveguide contactless connections, and are directly integrated within a single-layer. The meta-material-based gap waveguide is used; it enables a low-loss low-profile solution. The quasi-optical beamformer gives rise to a parallel-plate planar waveguide field which excites an array of contactless chip-to-waveguide transitions via step-tapered ridge gap waveguides. The other beamformer restores the field distribution (after amplification) and excites a wave going towards the waveguide output. Furthermore, the gap waveguide technology isolates the amplifiers from one another and provides a packaging solution in a single unit. The simulated return loss of the back-to-back structure is larger than 12 dB, while the insertion loss is smaller than 1.2 dB over the entire W-band (75–110 GHz).

A contactless, broadband and low-loss microstrip-to-groove gap waveguide transition operating at W-band is presented. The principle of operation is based on transforming EM fields from the SIW to the ridge gap waveguide mode via electromagnetic coupling. This is advantageous, since the proposed solution avoids the use of metal contact between the SIW and one of the waveguide parts. Furthermore, metamaterial-based gap waveguide technology provides a resonance-free packaging solution.