A gallium arsenide (GaAs)-based millimeter-wave broadband bandpass filter (BPF) is proposed based on slotted half-mode substrate integrated waveguide (HMSIW) spoof surface plasmon polaritons (SSPPs). The center frequency and bandwidth of this SSPP-based on-chip BPF can be easily controlled by tuning the geometry dimensions of the SSPP unit cell, which is attributed to its unique dispersion characteristics. For demonstration, a prototype of the proposed BPF is fabricated and experimentally characterized, with good agreement between the simulated and measured results. Due to the ability of the strong electric field confinement, the proposed on-chip SSPP structure has lower coupling feature with closely-spaced transmission line circuits than its counterpart traditional HMSIW structure.

This study presents a design of a 94-GHz high-performance and highly compact frequency-modulated continuous-wave radar sensor. In this sensor, an $X$ -band CMOS-based all-digital phase-locked loop chip, $W$ -band SiGe-based transceiver monolithic microwave integrated circuit (MMIC), and $W$ -band GaN-based MMIC power amplifier (PA) are heterogeneously integrated (HI). Each part of the 130-nm bipolar complementary metal-oxide-semiconductor (BiCMOS) SiGe-based transceiver MMIC is designed to include a low-noise amplifier, PA, octupler, mixer, and lange coupler. The fabrication process of our in-house silicon-based MEMS photosensitive composite film is developed to provide very high-density integration and very low insertion loss of interconnections between chips. The HI front end of the radar sensor is measured on-wafer with a high output power of 22 dBm. Moreover, a low double-sideband noise figure (NF) of 10.2 dB is obtained. Bonding–substrate integrated waveguide (SIW)–WG transitions between the heterogeneously integrated front end and the antenna are specially designed and verified. A 2.3-dB degradation is observed, where 19.7 dBm is measured at the transmitter WG WR-10-flange. Thus, the sensor offers a 55-dB dynamic range at a 2-m position with an expectation of a long-distance target-detection range. The radar sensor has an 11.7-cm range resolution and is only $60\times 40\times $ 8 mm ³ in size, with a weight of only 78 g.

In this letter, an on-chip bandpass filter (BPF) with ultrawide-stopband and high selectivity is designed and manufactured by 2-μm gallium arsenide (GaAs) HBT technology. For the sake of selectivity and rejection of the BPF, an extra pair of transmission zeros (TZs) locating at both sides of the passband is produced by introducing source-load coupling. Moreover, to improve the rejection of the BPF, a Pi-section circuit is designed so that a TZ is obtained at the upper sidebands. The measurement results show that the bandwidth covers 2.4-4.3 GHz, while its insertion loss is 2.05 dB at 3.35 GHz. In addition, this BPF achieves more than 30-dB sideband suppression format both at 0-1.3 GHz and 5.6-40 GHz. The BPF size is very compact only, i.e., 0.6 mm × 1.5 mm (0.02λg × 0.05λg); to the best of our expertise, this is the widest sideband suppression with such a compact on-chip size.

In this letter, an improved balanced Colpitts voltage-controlled oscillator (VCO) with a collector-emitter cross-coupled capacitors is presented. The proposed Colpitts structure can introduce a more robust oscillation startup condition. The noise-shifting technique is used to enhance the loaded quality factor of the tank, which improves the phase noise in turn. In addition, three-bit switches composed of enhancement-mode high-electron mobility transistors (E-HEMTs) are utilized to expand the tuning range and reconfigurability of the proposed VCO. In proof of the concept, a VCO prototype is fabricated in a GaAs BiHEMT [enhancement- and depletion-mode high-electron mobility transistor (E/D-PHEMT)] process. The measured results demonstrate the best phase noise of -139.46 dBc/Hz at 1-MHz offset. To the best of our knowledge, this is the lowest phase noise among the reported ones fabricated on-chip with a similar frequency band, and it achieves a wide tuning frequency bandwidth of 21% (2.65-3.27 GHz) with peak figure of merit (FoM) of -192.26 dB and FOMT of -198.8 dB.

In this letter, a 75.1-151.4-GHz silicon power amplifier (PA) is devised with the help of sandwiched slab transformer, which is proposed to increase the tuning ranges of coupling coefficient, quality factor, and conductivity. Being compact in size and simple in implementation enables it to be well-applied in multiple-way power combination. Based on this device, the fabricated PA in the 130-nm silicon germanium (SiGe) process demonstrates more than 14.1-dB gain at full W-band and 77% of the D-band. From 75 to 117.7 GHz, its measured Psat is all above 16.8 dBm, while its peak point is 19.8 dBm at 100 GHz with 8.8% PAE.