Encouraged by the proliferation of the 802.15.4a/z IR-UWB standard, the next generation, the 802.15.4ab, aims to extend the ranging distance by including a provision for narrowband radio assistance. Such a narrowband RX needs to achieve $\sim 3 ~\text{dB}$ NF while co-existing with WiFi blockers. We propose a $2^{\text{nd }}$-order TIA and a high dynamic range clip detector for the narrowband RX, achieving 9dB higher dynamic range than the state-of-the-art at a comparable NF and 2.5x the RF operating frequency. RX realized on a 22 nm CMOS node consumes $<6 ~\text{mW}$.

This letter presents an 802.15.4ab/a/z compatible IR-UWB 2TRX highlighting a full-duplex-based radar, a semisynchronous TX and TRX's digital baseband. A capacitive tuning technique proposed in the electrical balance duplexer (EBD)-based duplex RF front-end (RF-FE) improves TX-antenna insertion loss by 1.4 dB and the sensitivity of TX-RX isolation by 3.4 dB. The TRX achieves > 30-dB isolation while transmitting 500-MHz pulses centered at 8 GHz over 2VSWR antenna variation. The proposed asynchronous first-order-hold (FoH) switchedcapacitor power amplifier (SCPA) with a delay-locked-loop (DLL)-based calibration in TX achieves < -50 dBr alias sidelobes, 5 dB lower compared to the state-of-the-art (SoTA). The digital baseband supports next generation 802.15.4ab's sensing packets (SENS) and high-data-rate (HDR) mode. The 2TRX is implemented on a 22-nm CMOS process.

This work presents an 802.15.4ab/a/z compatible IR-UWB 2TRX highlighting a full-duplex-based radar and a semisynchronous TX. The matching and isolation techniques proposed in the electrical-balance-duplexer (EBD)-based fullduplex RF front-end (FE) enable state-of-the-art (SoTA) shortdistance radar performance at $1.7\times$ smaller form factor. An asynchronous first-order-hold (FoH) switched-capacitor power amplifier (SCPA) with a delay-locked-loop (DLL)-based calibration is proposed in the TX. This pushes the aliasing sidelobes to 5dB lower compared to the SoTA.

This article presents a battery-free system with a 6.78 MHz wireless power transfer (WPT) link for the long-term monitoring of the gastrointestinal tract. For this purpose, a 2.7x2.7 mm(2) Application Specific Integrated Circuit (ASIC) is developed and validated. It enables efficient power reception at microwatt power levels deep in the human body. The ASIC is interfaced to ultra-low power electronics that measure and wirelessly transmit data from ten sensor readouts suitable for use in ingestible sensing capsules. The system's ability to operate at a depth of 8 cm within human tissue while adhering to Specific Absorption Rate limits is demonstrated in an experimental setup.

The article presents a 16-output high-voltage (HV) compliant stimulator ASIC for selective neural stimulation. The ASIC supports temporal interference stimulation (TIS) to achieve high-spatial selectivity without requiring nerve-penetrating electrodes. A novel on-the-fly active charge balancing (CB) is proposed since existing CB solutions cannot be directly applied to TIS. Simultaneous electrode-tissue impedance (ETI) sensing is realized by reusing the CB hardware. The stimulator ASIC, fabricated in 130-nm bipolar-complementary metal-oxide- semiconductor-double-diffused metal-oxide-semiconductor (BCD) technology, occupies 0.29 mm2 per output and achieves 10V compliance while supporting up to 10-mA stimulation current and maintaining TIS steering flexibility. The proposed active CB approach compensates for electrode voltage drift during TIS based on a negative feedback loop, achieving a sub-10-nA mismatch current over a wide range of ETIs. The ETI sensing reuses the stimulation current and CB hardware for simultaneous measurements during stimulation, achieving a sensing inaccuracy of +/- 2 2 . Extensive saline experiments confirm the ability of the ASIC to achieve superior spatial selectivity for stimulation while maintaining proper active CB and simultaneous ETI sensing.

The vagus nerve (VN) is a key part of the parasympathetic nervous system connecting the brain to various organs. VN stimulation has been FDA-approved for treatment of drug-resistant epilepsy and depression and holds promise for chronic inflammation and arrythmia [1]. However, existing solutions either have poor spatial selectivity causing unwanted side effects or incur a high risk for nerve damage (Fig. 1). This work proposes non-penetrating high-density cuff electrodes driven by an ASIC that employs temporal interference stimulation (TIS) [2] to improve spatial selectivity (Fig. 1). In TIS, a pair of differential current stimulators generates two kHz-range semi-continuous sinusoidal currents with a small frequency offset (e.g. 10Hz). This creates an interference pattern within the tissue. Since neural cells are more receptive to low-frequency (LF), they would be entrained by the LF envelope. The stimulation intensity of the LF envelope can be steered to any location by selecting different electrode pairs and/or stimulation current amplitudes [2].

This article presents a low power, linear RF front-end (RF-FE) for an 802.15.4a/z compatible impulse-radio ultrawideband (IR-UWB) receiver. A complementary topology-based LNA is proposed with a bandpass filter (BPF) integrated into its output. The LNA includes a complementary common gate (CCG) stage to isolate the BPF from the undesired loading of the LNA’s input stage to achieve a high $Q$ and 5-to 10-GHz tuning range. This CCG stage relaxes a trade-off between headroom and linearity. Furthermore, capacitive and transformer coupling techniques are proposed in the LNA to increase its OP1dB and second-order intermodulation (IM2) by 4 and 27 dB, respectively, compared to noncomplementary counterparts without these techniques. An automatic feedback-based back-gate biasing technique is proposed for the variable gain transconductance amplifier (VGTA) following the BPF to increase VGTA’s transconductance range for a given width over length (W/L). The receiver is fabricated in a 22-nm fully depleted silicon on insulator (FDSOI) CMOS. The measured results over the 5-to 10-GHz RF frequency range show a minimum noise figure (NF) of 6 dB and a blocker resilience of $-$ 17 dBm at 7.6-mW power dissipation.

802.15.4a/z enabled IR-UWB TRXs [1–4] are being widely deployed into secured ranging and precise localization applications thanks to their increased resistance against relay attacks and high reliability in non-ideal conditions (e.g., non-line of sight, fading), respectively. However, the recent approval of Wi-Fi 6E (by FCC) in the 6-to-7.125GHz spectrum with up to 25dBm EIRP, demands a significant increase in the blocker performance of the existing 802.15.4a/z receivers. This poses a severe challenge to the further proliferation of 802.15.4a/z applications, especially involving mobile and IoT devices, which also need low-power consumption for battery-powered operation.

This work presents an IEEE 802.15.4a/4z compliant IRUWB transceiver for high-precision ranging. By virtue of the proposed digital deserialization-serialization, the TX can generate the Inter-Symbol-Interference (ISI) free IEEE 802.15.4a/4z packet. The proposed analog Finite Impulse Response (FIR)-based TX pre-emphasis improves $3.5 \times $ ranging precision without substantial power overhead and fulfills the spectrum requirement of the standard and the worldwide UWB regulations. The presented transceiver consumes 8.7 mW in TX mode and 21 mW in RX mode.

This letter presents an IEEE 802.15.4a/4z compliant IR-UWB transceiver for high-precision ranging. By virtue of the proposed digital deserialization–serialization, the TX can generate the intersymbol-interference (ISI)-free IEEE 802.15.4a/4z packet. The proposed analog finite impulse response (FIR)-based TX pre-emphasis improves $3.5\times $ time-of-arrival (ToA) measurement precision without substantial power overhead and fulfills the spectrum requirement of the standard and the worldwide UWB regulations. The presented transceiver consumes 8.7 mW in TX mode and 21 mW in RX mode.

The presented IEEE 802.15.4z IR-UWB transmitter is aimed at providing long battery life and compatibility with international standards. Thanks to the optimized pulse shaper and pulse combiner, the sidelobe power is <-29dBc, required for ETSI compliance at 6.5GHz. Extensive duty-cycling in the RF oscillator and the TX enables a low power consumption of 380μW, which is 10× better than state-of-the-art low side-lobe IEEE 802.15.4z transmitters.

Using IR-UWB for accurate battery-powered localization requires low energy consumption and high interference resilience. The presented IR-UWB 802.15.4z transceiver features low power consumption thanks to its inverter-based RX architecture and polar TX. The two-stage distributed PLL enables simultaneous multi-channel reception, reducing the energy consumption and measurement time of localization. It consumes 8.9mW in TX mode and 21.5mW/ch. in RX mode while achieving -33dBm OOB blocker tolerance.

This article presents an injection-locked (IL) ring-oscillator-based fractional- ${N}$ digital phase locked loop (DPLL) supporting Bluetooth low energy (BLE) frequency modulation with an frequency-shift keying (FSK) error between 2.4% and 3.3%. As the fractional spur cannot be suppressed by IL-DPLL, this work proposes a random edge injection (REI) to reduce the spur. This technique also speeds up the convergence time of gain calibration of the digital-to-time converter (DTC). Furthermore, the proposed background calibration schemes allow the DPLL to achieve stable performance across all BLE channels, including both integer- ${N}$ and fractional- ${N}$ channels. This work was fabricated in the 40-nm CMOS technology occupying a 0.09-mm 2 area. A fractional spur of −44 dBc and a reference spur of are achieved while consuming 2.76 mW when REI is activated. The background calibrations also ensure stable performance across BLE channels.

Recent advances in wearables allow for monitoring the health status of users without disturbing their daily lives (Fig. 22.5.1). Bio-Impedance (BIOZ) is an interesting sensing modality for impedance cardiography, respiration measurement, and body composition analysis [1–4]. However, existing solutions rely on a 4-electrode measurement, where two leads are used for the current generator (CG), and the others for the readout front-end (RFE). This eliminates the effect of the electrode-tissue impedance (ETI) and measures the actual BIOZ, which is required in body composition analysis where the absolute value is important. However, this degrades user comfort and adds to system complexity and cost. This work proposes a BIOZ readout IC supporting 2-electrode BIOZ measurement of body signals, where relative changes over time yields the desired information (heartrate, respiration, etc.), with a good accuracy as a 4-electrode setup (Fig. 22.5.1). The ASIC can even measure the heartrate at the wrist via 2 electrodes, which consumes significant less power than the Photoplethysmography.

Continuous vital-sign monitoring is of paramount importance in remote heath monitoring or rehabilitation environments for chronic diseases. Medical-grade wireless and wearable bio-sensor systems that can be used at home offer a much more attractive solution than hospital-based monitoring systems. We report an all-in-one battery-powered SoC designed for low-cost single-use health patches (Fig. 22.1.1), allowing continuous monitoring in a home setting to improve patient comfort and reduce cost of care by, e.g., reducing hospital stays. In addition to medical-grade signal quality, low power consumption is key in such a health patch system, to enable a comfortable form factor with miniature battery size and prolong the operational lifetime to at least several weeks.

This letter presents a 5-channel unipolar fetal electrocardiogram readout IC for monitoring the health of a fetus during pregnancy. Each readout channel includes an instrumentation amplifier, a programable gain amplifier and a successive approximation register ADC. A unipolar, common half branch reuse topology is used to achieve low noise, low power, low crosstalk between the channels high input impedance and high CMRR at the same time. Each channel achieves an input referred noise of 0.47 µVrms in 0.5 to 150 Hz, while consuming a power of 43.2 µW. The 5-channel system provides a CMRR of 98 dB and an interchannel crosstalk rejection of 95 dB. The chip is implemented in a standard 55-nm CMOS process and occupies an area of 4.0 mm2. The whole chip, including five readout channels, leadoff detection, reference generation, autonomous data acquisition with on-chip sample storage and an interrupt-based serial peripheral host interface consumes a total power of 258 µW.

An all-in-one battery powered low-power SoC for measuring multiple vital signs with wearables is proposed. All functionality needed in a typical wearable use case scenario, including dedicated readouts, power management circuitry, digital signal processing and wireless communication (BLE) is integrated in a single die. This high level of integration allows an unprecedented level of miniaturization leading to smaller component count which reduces cost and improves comfort and signal integrity. The SoC includes an ECG, Bio-Impedance and a fully differential PPG readout and can interface with external sensors (like an IMU). In a typical application scenario where all sensor readouts are enabled and key features (like heart rate) are calculated on the chip and streamed over the radio, the SoC consumes only 769W from the regulated 1.2 V supply.

This paper presents an ultra-low-power (ULP) IEEE 802.11ah fully-digital polar transmitter (TX). IEEE 802.11ah is a new Wi-Fi protocol optimized for Internet-of-Everything (IoE) applications. Compared to other IoE standards like Bluetooth or ZigBee, its sub-GHz carrier frequency and mandatory modes with 1MHz/2MHz channel bandwidths allow devices to operate in a longer range with scalable data-rates from 150kb/s to 2.1Mb/s. Moreover, the use of OFDM improves link robustness against fading, especially in urban environments, and achieves a higher spectral efficiency. The key design challenges of an IEEE 802.11ah TX for IoE applications are to meet the tight spectral mask and error-vector-magnitude (EVM) requirements as for conventional Wi-Fi standards (e.g., 802.11n/g), while achieving low power consumption required by IoE applications. The presented TX applies a fully-digital polar architecture with a 1V supply, and it achieves more than 10× power reduction compared to the state-of-the-art OFDM transceivers [1-4]. Without any complicated PA pre-distortion techniques as in [5], it passes all the PHY requirements of the mandatory modes in IEEE 802.11ah with 4.4% EVM, while consuming 7.1mW with 0dBm output power.