In this work, we propose a multi-bit precision (4b input, 4b weight and 4b output) in-memory computing (IMC) architecture, based on the voltage scaling and charge sharing scheme, for the artificial intelligence (AI) edge devices. To achieve the efficient computation, a new AND logic based 8T SRAM cell (AND8T) has been used which employs the charge-domain based computation. For such computation, AND8T incorporates an overlaying metal-oxide-metal capacitor (MOM cap) with no bitcell area overhead. The proposed cell mitigates the linearity issue of multiply and accumulate (MAC) operation for the IMC unit which is highly desirable for the reliable operation of complex neural networks (CNN). Moreover, our high precision AND8T based IMC architecture allows 128 parallel MAC operations avoiding the need of serial multi-bits input implementation through multiple cycles. The proposed design has been successfully verified by the monte carlo simulation results while working at 50MHz clock frequency and 1V supply using standard 65nm node.
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.
In this paper, a low power asynchronous successive approximation register (SAR) analog-todigital converter (ADC) involving the process, voltage, and temperature (PVT) compensation is presented. A proposed adaptive conversion time detection-and-control technique enhances the power efficiency, covering wide PVT variations. The proposed detection-and-control technique senses PVT variation in an aspect of conversion time, and adaptively controls the operation speed and power consumption. For PVT compensation, the proposed architecture includes the local supply/ground voltage. The local supply/ground voltage makes high |VGS| for transistors in the comparator and capacitive digital-to-analog converter switches, resulting in enhanced operation speed. However, when PVT condition changes to be favorable for the conversion speed, the |VGS| decreases for low power consumption. 30 chips were measured to verify the proposed ADC. Having the proposed architecture tested with 10 kHz input frequency, SNDR remained higher than 60 dB at unfavorable conditions such as-9 % supply voltage variation, or-20 ⁰C temperature variation. On the other hand, at favorable conditions such as +9 % supply voltage variation, or 80 ⁰C temperature variation, the power consumption of SAR ADC decreased without performance degradation. INDEX TERMS Asynchronous, compensation, low power, process voltage temperature (PVT), successive approximation register (SAR) analog-to-digital converter (ADC)
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