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In this brief, a harmonic-controlled substrate-integrated defected ground structure (SIDGS) resonator with tuning capacitor is proposed for the design of tunable filter. Such resonator exhibits a harmonic-controlled characteristic. The fundamental resonant frequency can be properly tuned, while the spurious resonance is controlled at much higher frequency to achieve a wide stopband. To verify the principle, a tunable bandpass filter (BPF) is designed and fabricated based on the resonator. The center frequency can be tuned from 1.75 to 2.7 GHz. Meanwhile, the stopband can extend up to 9.5 GHz with a rejection level of 20 dB for all tuning cases. The BPF also exhibits low insertion loss (i.e., 1.1–1.9 dB) and compact size (i.e., 0.07 ${\lambda _{g}}\,\,{\times }\,\,0.08\,\,{\lambda _{g}}$ , where ${\lambda _{g}}$ is the microstrip guided wavelength at the 1.75 GHz). [ABSTRACT FROM AUTHOR]

This article presents a 22.6–39.2-GHz reflectionless receiver (RX) capable of reducing the in-band intermodulation and high-order mixing products. Such RX consists of an absorptive IF amplifier, a double-balance passive mixer, and a dual-path noise-canceling low noise amplifier (LNA). The absorptive IF amplifier is utilized to suppress the out-of-band signal reflected back to mixer, which can reduce the intermodulation and high-order mixing products caused by the remixing of the out-of-band signals. Meanwhile, the dual-path noise-canceling LNA is used for achieving low noise figure (NF) in a wide frequency range. To verify the aforementioned principle, a reflectionless RX is implemented and fabricated using a conventional 28-nm CMOS technology. The measurement shows the minimum NF of 3.6 dB and the peak input third-order intercept point (IIP3) of −11.7 dBm. Besides, the proposed RX can support multi-Gb/s, 256-quadratic amplitude modulation (QAM)/1024-QAM modulation signals. [ABSTRACT FROM AUTHOR]

This article presents a quadrature switched/floated capacitor power amplifier (SFCPA) with deep back-off efficiency enhancement. The SFCPA is introduced to decrease the dynamic power consumption at power back-off (PBO), which could improve the system efficiency (SE). The reconfigurable self-coupling canceling transformer (RSCCT) with enhanced tuning range of turn ratio is used to achieve impedance boosting for further improved efficiency at deep PBO. Based on the proposed SFCPA, a watt-level quadrature digital power amplifier (DPA) with IQ cell sharing, hybrid Doherty, and impedance boosting is proposed for deep PBO efficiency enhancement. Implemented in 40-nm CMOS, the proposed DPA with 1.2-/2.4-V supply achieves 30.3-dBm saturated output power ($P_{\mathrm{ out}}$) with 36.6%/32.9%/29.1%/23.7%/18.6%/13.2% SE for 0-/3-/6-/9-/12-/15-dB PBOs at 2.4 GHz. For 60-MHz 256-QAM modulation signal, it delivers 23.32-dBm average output power ($P_{\mathrm{ avg}}$) with an error vector magnitude (EVM) of −31.9 dB and an average drain efficiency (DE) of 30.7%. For 40-MHz 1024-QAM signal, it shows 20.44-dBm $P_{\mathrm{ avg}}$ with an EVM of −35.9 dB and an average DE of 22.6%. [ABSTRACT FROM AUTHOR]