An ultra‐wideband (UWB) low‐noise amplifier (LNA) implemented using 180 nm complementary metal–oxide–semiconductor technology is presented for wireless personal area network (WPAN) and wireless body area network (WBAN). Increasing the resistance of the substrate resistor RB reduces the noise factor. When additional substrate resistors and a composite feedback topology are employed, the proposed LNA can achieve both a 1.4 dB reduction of the noise figure (NF) and a 4 dB enhancement in power gain (PG). Over the operating frequency range from 3.1 to 4.8 GHz, the LNA achieves a maximum PG of 14.5 dB, a minimum NF of 1.5 dB, and an input return loss of <10 dB. The measured current consumption is 3 mA with a 1.5 V supply voltage. The active chip area is 0.008 mm2. The proposed 3.1–4.8 GHz LNA has a superior NF, smaller active area, and the lowest dc power consumption compared with devices reported in the literature.

In this paper, a new low-profile smart multiple-input multiple-output (MIMO) antenna system is presented for WiFi IEEE 802.11a/b/g/n/ac/ax applications. The proposed compact 2.4-GHz antenna system employs two beam-switching antenna cells for MIMO operation. Each antenna cell is composed of four reconfigurable frequency-selective reflectors (RFSRs) and a one-to-four switching feeding network. The RFSRs are constructed using a one-wavelength metal loop resonator, which functions as a radiating antenna or a wave reflector to reflect beams along a specific direction, as controlled by the switching network. The feeding switching network utilizes PIN diodes to adjust the phase and impedance required for changing the operational status of each RFSR. The overall dimensions of the antenna system, including the metallic ground, are 120 mm ´ 120 mm ´ 9.5 mm. Moreover, the measured operational bandwidth of the 2.4-GHz antenna is approximately 100 MHz, and the radiation efficiency of each directed beam is 40%–70%.

This paper presents a triple-band low-noise amplifier (LNA) fabricated using a 0.18 μm Complementary Metal-Oxide-Semiconductor (CMOS) process. The LNA uses a double-peak load network with a switched component to accomplish the triple-band operation. Moreover, noise reduction using a substrate resistor to ameliorate the noise performance is presented. Noise reduction of 1.5 dB can be achieved at 2.5 GHz without additional dc power and extra manufacturing costs. An input matching technique is realized simultaneously using a gyrator-based feedback topology. The triple-band LNA can be realized by using a dual-band input network with a switched matching mechanism. The target frequencies of the triple-band LNA are 2.3–2.7 GHz, 3.4–3.8 GHz, and 5.1–5.9 GHz, covering the operating frequency bands of time-division long-term evolution (TD-LTE), mid-band Fifth-generation (5G), LTE-unlicensed (LTE-U) band, and Wireless LAN (WLAN) technology. The measured power gains and noise figures at 2.5, 3.5, and 5.2 GHz are 12.3, 15.3, and 13.1 dB and 2.3, 2.2, and 2.6 dB, respectively.