Compact low dropout (LDO) with high current handling capability and superior transient response is gaining increasing attention for the battery-powered 5G mobile applications. In this article, a new multiple-loop design technique for fast-transient response LDO regulator design has been proposed and successfully implemented in a 0.13-μm SOI CMOS process for portable smartphone and tablet PC applications. Its supply current capacity is more than 1 A, and its output voltage is from 1.2 to 1.8 V. The proposed LDO features a 10-mV undershoot and overshoot with 1-A/100-ns load current on a 1-μF output capacitor. This superior transient performance is achieved by embodying a novel frequency compensation scheme without penalty of dc loop gain drop in large load current conditions. The dc loop gain is 60 dB and constant regardless of the fact that the load current varies from 0 to 1 A. This contributes to a small load regulation and line regulation of 0.6 μV/A and 0.23 mV/V, respectively. The LDO consumes 35-μA quiescent current in the mission mode and 5 μA in the standby mode. The LDO silicon size is 325 μm x 106 μm.

In this article, an X-band complementary metal-oxide-semiconductor (CMOS)-integrated phased-array radar sensor is proposed to enable the subject localization and multimodal vital sign monitoring. With the accurate beam-steering (ABS) technique realized by both true-time delay and phase shifting at the transmitter, the phased-array radar sensor achieves 60° steering coverage for the locating and monitoring on the targeted subjects with fine beam-steering precision. With the interferometric time-phase analysis (ITPA) algorithm adopted to the dechirped signal at the receiver, the vital signs and falling are detected by the radar sensor. Fabricated in 65-nm CMOS technology, the radar sensor occupies 5.8 mm² of silicon area and consumes 740.7-mW power. A series of experiments was carried out to demonstrate the capabilities of the prototype radar sensor on localizing the targeted subjects, discerning vital signs, and detecting falling in a wide field of view (FoV).

A pulsed chirping phased-array transceiver (TRX) is demonstrated for X-band synthetic aperture radar (SAR) application. The phased-array TRX is implemented on a single CMOS chip with beamsteering/beamforming capabilities. The chip-scale radar TRX is composed of four transmitters (TXs) and four receivers (RXs) operating at 10-GHz center frequency with 1-GHz bandwidth (BW). To achieve the wideband beamsteering with a fine angle step, the two-stage delay control in the TX is proposed, where a delay-locked loop (DLL) -based multi-phase synthesizer (MPS) is used to control the coarse true-time delay of the baseband chirp, and the active phase shifters (PS) in radio frequency (RF) path are used for fine phase tuning. Fabricated in a 65-nm CMOS technology, the TRX consumes 228 mW for each channel at a 1.2-V supply, delivering ~10.2-dBm power with <1.3-dB ripple. The delay-line test shows that the dechirped signal achieves -13-dB peak-to-sidelobe ratio (PSLR) and the phase coherence error is within ±1.2° at a chirp rate of 1 MHz/μs. The prototype phased-array radar TRX chip is demonstrated with the antenna arrays consisting of Vivaldi antennas of 8-dBi gain, 6-GHz BW, and 6-cm pitch distance. Experiments indicate that beamsteering/beamforming up to ±60° with a step of ~1° is achieved. SAR imaging experiment is carried out based on both the two-stage beamsteering in the TXs and the digital beamforming in the RXs, proving the capability of the prototype phased-array radar TRX chip for the SAR imaging applications.

Malaria parasite- Plasmodium falciparum infection is a severe healthcare problem in tropical and subtropical regions. Early detection of such disease is vital in reducing mortality and controlling the spread in the affected areas. In this article, detecting the ring-stage malaria parasite is carried out by using the proposed photoacoustic (PA)-surface acoustic wave (SAW) sensing and detection system. By optical radiation, the PA signal is generated from the red blood cell (RBC), and then, the SAW sensor could transfer the acoustic wave into the electrical signal for the analysis. The SAW sensor is manufactured via the standard two-step lithography techniques. The proposed system consists of a tunable pulse laser device with the adjusting optical components, a PA-SAW sensor, a function generator, two analog front-end (AFE) circuits, a digital oscilloscope, a workstation for data postprocessing, and several auxiliary coaxial cables for data communications. With the acquired PA signal and its fast Fourier transform (FFT) spectrum from the various specimens, the cultured ring-stage malaria parasite in the infected whole blood could be detected at a low concentration level of 0.5% with the PA-SAW sensor. The proposed system demonstrates its excellent potential in the early diagnosis of the malaria parasite.

Ultra-high frequency (UHF) partial discharge (PD) detection is essential for routine maintenance of gas-insulated switchgear (GIS). Realizing low-noise detection with cost-effectiveness and ease of installation is promising but challenging. This paper presents a novel broadband noise-shaping network (BNSN) integrated with a printed monopole antenna (PMA) sensor to realize sufficient noise rejection and good impedance matching. Moreover, by analyzing the equivalent noise circuit and codesigning a high-speed preamplifier circuit with the proposed sensor, the detection sensitivity and anti-interference of the proposed sensor module are improved. The effectiveness and superiority of the proposed sensor are first verified in accordance with IEC 62478, followed by validations using a PD simulator and a real 24-kV GIS. The experimental results demonstrate that the proposed sensor module has the capability to identify different PD types even in noisy environments.

This article presents an ultralow-power (ULP) microelectromechanical system (MEMS)-based phase-tracking frequency shift keying (FSK) transceiver (TRX) with an embedded envelop detector-based on–off keying (OOK) wake-up receiver (WuRX). The system supports a shared antenna interface of FSK-matched filter for TRX and a matching network for the FSK receiver (RX) and OOK WuRX. To consume less power, the transmitter employs an adaptive fast switching (AFS) technique for FSK/OOK modulator and uses a high-Q MEMS resonator to get frequency stability. In addition, for better interference filtering, the MEMS-based modulator is shared to provide LO in FSK RX as it owns inherent sidelobe suppression. To support higher blocker/interference rejection with relatively low power, MEMS-based FSK-matched filter plus matching network with current-reuse LNA is co-designed to provide additional passive gain. Fabricated in 65-nm CMOS process, the transmitter (TX) generates FSK signals of $-$ 11.2 dBm output power at ISM-915 MHz and the data rate is up to $6$ Mb/s. At $1$ MHz offset, the measured phase noise (PN) is $-$ 140.2 and $-$ 139.3 dBc/Hz at 926.3 and 932.4 MHz, respectively. By sharing the modulator, the RX exhibits $-$ 36.2 dB in-band signal-to-interference ratio (SIR), $-$ 77.5 dBm sensitivity at bit error rate (BER) of 10 $^{-3}$ working under $2$ Mb/s data rate. The TX, FSK RX, and WuRX consume 642 $\mu$ W@6 Mb/s, 520 $\mu$ W@2 Mb/s, and 86 $\mu$ W@200 kb/s, leading to the energy efficiency of 107, 260, and 430 pJ/b, respectively. The proposed TX achieves over 1.5 $\times$ better energy efficiency than state-of-the-art results and the FSK RX attains the best FoM with the sensitivity of $-$ 77.5 dBm, which are well suited for energy-efficient pico-IoT applications.