Time-Interleaved SAR ADC with Background Timing-Skew Calibration for UWB Wireless Communication in IoT Systems

Abstract

Ultra-wideband (UWB) wireless communication is prospering as a powerful partner of the Internet-of-things (IoT). Due to the ongoing development of UWB wireless communications, the demand for high-speed and medium resolution analog-to-digital converters (ADCs) continues to grow. The successive approximation register (SAR) ADCs are the most powerful candidate to meet these demands, attracting both industries and academia. In particular, recent time-interleaved SAR ADCs show that multi-giga sample per second (GS/s) can be achieved by overcoming the challenges of high-speed implementation of existing SAR ADCs. However, there are still critical issues that need to be addressed before the time-interleaved SAR ADCs can be applied in real commercial applications. The most well-known problem is that the time-interleaved SAR ADC architecture requires multiple sub-ADCs, and the mismatches between these sub-ADCs can significantly degrade overall ADC performance. And one of the most difficult mismatches to solve is the sampling timing skew. Recently, research to solve this timing-skew problem has been intensively studied. In this paper, we focus on the cutting-edge timing-skew calibration technique using a window detector. Based on the pros and cons analysis of the existing techniques, we come up with an idea that increases the benefits of the window detector-based timing-skew calibration techniques and minimizes the power and area overheads. Finally, through the continuous development of this idea, we propose a timing-skew calibration technique using a comparator offset-based window detector. To demonstrate the effectiveness of the proposed technique, intensive works were performed, including the design of a 7-bit, 2.5 GS/s 5-channel time-interleaved SAR ADC and various simulations, and the results prove excellent efficacy of signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) of 40.79 dB and 48.97 dB at Nyquist frequency, respectively, while the proposed window detector occupies only 6.5% of the total active area, and consumes 11% of the total power.

Anomaly Intrusion Detection of Wireless Communication Network-Based on Markov Chain Model

“…As the name implies, it attempts to detect, identify, and isolate intrusion attempts or unauthorized use of computers [11]. With the continuous discovery of system vulnerabilities and attacks, the status of the intrusion detection system in the whole security system continues to improve, and its role is becoming greater and greater [12]. Figure 1 shows the research on the design method of intrusion detection system for the wireless network.…”

Categorization and Characterization of Time Domain CMOS Temperature Sensors

“…The temperature estimation function of this type of time domain CMOS temperature sensor is defined as the ratio of two different temperature dependent delay times. The typical structure of this type of temperature sensor, which was proposed by P. Chen et al in 2010 [38], includes two delay lines, of which delay times vary in a different way from each other with respect to temperature, and a successive approximation register (SAR) control logic [76][77][78][79][80][81][82][83][84][85][86][87] implemented as an FSM. For example, if one of these delay lines is composed of the general inverter type delay cells of Figure 5b, then the other is composed of the delay cells shown in Figure 6b which are less sensitive to temperature [33,38].…”

An 11.8-fJ/Conversion-Step Noise Shaping SAR ADC with Embedded Passive Gain for Energy-Efficient IoT Sensors

“…Ultra-low power consumption is required in these systems for signal sensing and processing to provide a long battery life. An analog-to-digital converter (ADC) is a key component in the processing of sensor output [ 1 , 2 , 3 ] and wireless communication [ 4 , 5 ]. Among various ADCs, successive approximation register (SAR) ADC is suitable for achieving high energy efficiency with low power consumption [ 6 ].…”