Hakon A. Hjortland

We report a direct-RF pulse-based radar System on Chip (SoC) with applications in vital signs monitoring and occupancy detection. The transmitter complies with FCC, ETSI, and KCC regulatory masks with −10 dB bandwidths of 1.4 and 1.5 GHz centered at 7.29 and 8.748 GHz. The receiver samples the reflected signal at 23.328 GS/s, covering a 9.9-m consecutive range. The measured front-end noise figure is 6.3 dB with 14.7-dB gain at 7.29 GHz. Chest movements from breathing and heartbeats in a human subject were detected at 9 and 5 m, respectively. All required power management and clock functions are integrated on-chip. The SoC was implemented in 55-nm CMOS. In active mode, the system consumes 118 mW from a 1.8-V power supply.

Radar sensors find use in a wide range of applications [1–4]. Impulse radars operating below 10GHz offer opportunities in applications including non-contact vital signs monitoring, such as breathing and heart rate, presence detection, and ranging. However, the wide instantaneous bandwidth incurs a power penalty from the ADC, calling for unconventional receiver (RX) architectures [4, 5]. In practical use, the received power from narrowband interferers, such as 802.11, can be much larger than the echo from the targets, requiring an unnecessarily large RX dynamic range. In this paper we report an impulse radar SoC (shown in Fig. 7.7.1), featuring a transmitter (TX) that complies with regulations for unlicensed operation, 1b direct RF sampling, and RF interference rejection. The system is self-contained, including power management and clock generation functions, and requires only an external crystal and antennas to operate.

This paper presents a fully CMOS integrated Impulse Radio Ultra Wide Band (IR-UWB) based radar transceiver applied in remote respiration- and heart-rate monitoring. The combination of high bandwidth and direct RF sampling offers fine spatial resolution and accuracy along with flexibility in the application-level signal processing. The high-speed RF sampling is enabled by a time-interleaved Analog-to-Digital Converter relying on the inherent coherency of radar TX/RX. The topology is based on Continuous Time Binary Valued (CTBV) signal processing moving design constraints from the amplitude domain to the time domain adapting to the very short time-constants offered by modern CMOS technology. The primary focus of this paper is to explore the use of UWB radar technology in health and medical applications, where the offered combination of high resolution and penetration abilities is a major advantage. In addition to covering the actual radar sensor, embedded signal processing based on Pulse-Doppler time-frequency analysis is utilized in a fully self-contained radar module. Measured results of vital signs in different scenarios are presented and discussed.

This brief presents a continuous-time impulse radio ultrawideband transmitter. The transmitter is a part of a high-precision ranging single-chip transceiver that measures the time-of-flight symbol propagation. The clock burst generator in the transmitter will initiate symbol transmission in continuous time unbounded by any clock signal while maintaining an accurate chip rate during symbol transmission. Using a calibration circuit, the clock period can be programmed precisely to compensate for device mismatch. The transmitter is fabricated in Taiwan Semiconductor Manufacturing Company 90-nm CMOS technology and occupies an area of 0.123 mm². The programmable clock range is from 12.65 to 111 MHz, and the measured rms jitter is 3.26 ps at 50 MHz. The entire transmitter has a power consumption of 1.41 mW at the data rate of 2 Mbit/s.

A linear impulse radio ultra wideband MIMO radar array is presented. The IR-UWB imaging array is true time delay based. The imaging system is implemented using an impulse radio radar transceiver which is realized in 90 nm CMOS technology. The transceiver has programmable coarse, medium and fine delay lines which facilitate an electronic beamsteering with high resolution. A calibration circuit and scheme for precise delay adjustment of antenna elements are presented. Tapered slot Vivaldi antennas are used in both of the transmit and receive arrays. The MIMO radar array is modeled in MATLAB. Using the accurate calibration procedure, measurement results agree very well with the simulation results. A clutter map removal method is used for reducing the antenna elements cross-talk effect and the static variations to improve the image quality. The effects of different array parameters such as inter element spacing and number of transmit and receive antenna elements on the array pattern in terms of resolution and signal to noise ratio are studied to optimize and enhance the MIMO radar array performance.

A novel inductorless tunable switched-capacitor band-pass filter based on N-path periodically time-variant networks is presented. The proposed UWB band-pass filter is complete with ring-oscillator used for multi-phase clock generation suitable for power-efficient IR-UWB systems. The filter prototype was fabricated in TSMC 90 nm CMOS, and occupies a chip area of 0.004 mm 2 . It archives a -3 dB bandwidth of 2 GHz while the center frequency can be tuned from 4 GHz to 4.4 GHz. Power consumption is 1.1 mW from 1.2 V supply voltage, and the performance was verified experimentally.

An UWB impulse radio receiving antenna array based on delay and sum beamforming is presented. The array is implemented using a simple impulse radio radar transceiver. The presented radar transceiver is fabricated in 90 nm TSMC technology, and it has a high speed sampler with sampling rate of 10 GHz which recovers the received signal with sufficient resolution. Using a programmable delay element with medium and coarse settings, an electronic beam steering step of about 10-15° is feasible. A high precision calibration circuit is explored for delay adjustment with high resolution. The measurement results show that the array with antenna spacing of about one wavelength has a cross-rang resolution of 17 cm, which is about one and half of the wavelength.

This paper presents a impulse-radio ultra-wideband (IR-UWB) receiver front-end covering the frequency band of 3-5 GHz intended for low power, low data-rate communication over a relative short range for such applications like wireless sensor networks (WSNs). The receiver front-end was designed and verified in 90 nm CMOS provided by TSMC. It employs direct-conversion (homodyne) architecture, and occupies a chip area of 0.9 mm 2 . The receiver exhibits a peak gain of 45 dB at 4 GHz, and consumes a total power of 26.6 mW from a 1.2 V supply voltage. Input return loss, S 11 ≤ -12 dB, and noise figure (NF) is between 8 dB and 9 dB through 3-5 GHz bandwidth.

Precision ranging is a key factor for localization in wireless sensor networks. Most reported ranging solutions are limited by clock frequency or clock synchronization. With the combination of continuous-time binary value (CTBV) technique and the impulse-radio ultra-wideband (IR-UWB) technology, we have a promising approach towards high precision positioning combined with communication. In this paper, we have presented a UWB communication solution with embedded ranging by measuring the symbol round trip time without a common reference clock. A first working clockless UWB ranging transceiver realized in 90 nm CMOS technology with fully integrated digital symbol detection including a running cross-correlator is implemented. Preliminary measured results shows that two transceivers in a master-slave configuration can estimate distance with centimeter precision (≈ 1.4 cm).