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Martin Ruskowski - IEEE Xplore Author Profile

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Level-crossing (LC) ADCs are superior choices for digitizing sparse input signals, which have short bursts of activity followed by long periods of silence. Monitored by a continuous-time (CT) comparator, the input signal is only processed after crossing a predefined voltage. This event-driven working scheme results in concentrated conversions solely during active periods, significantly reducing po...Show More
This work presents a highly compatible dual-mode continuous-time (CT) delta-sigma analog-to-digital converter (ADC) that can be applied to continuous or sample-by-sample acquisitions. According to different scenarios, based on a compact 3rd-order CT delta-sigma loop filter using a 17-level quantizer, it can be easily configured as either a CT delta-sigma modulator (DSM) or a CT incremental ADC (IA...Show More
This paper describes the analysis and design of a discrete-time (DT) fully dynamic 3-0 multi-stage noise-shaping (MASH) delta-sigma (ΔΣ) analog-to-digital converter (ADC). Through system-level analysis, error source analysis, nonlinearity analysis and modeling of the integrators, and detailed considerations for circuit implementation, the trade-offs between design parameters in the 3-0 MASH ΔΣ ADC...Show More
The ever-hungry computing needs for data centers and automotive applications require a large output current at sub-1 V voltages. On the other hand, the input voltage of power converters must be raised to ease the 12R loss on the system voltage bus. The high input voltage and large output current requirements impose significant challenges on the converter efficiency, density, and speed, which are a...Show More
This paper demonstrates the design of a high-resolution continuous-time (CT) incremental delta-sigma (I-ΔΣ) analog-to-digital converter (ADC). A zero-order successive approximation register (SAR)-assisted extended counting is adopted to achieve higher resolution without affecting the thermal noise performance and conversion time. Acting like a 2-0 multi-stage noise-shaping (MASH) structure, achiev...Show More
This article presents a two-stage pipelined noise-shaping (NS) successive-approximation-register (SAR) analog-to-digital converters (ADCs) for sub-micro-watt and high-resolution applications. However, it asks for an accurate residue amplification to avoid severe quantization noise leakage from the frontend stage. Therefore, a charge-efficient correlated-level-shifting (CECLS) assisted residue ampl...Show More
This article presents a dual-path series-capacitor (DPSC) converter with a voltage range of 9~{\sim }~16 -V input to 1-V output. By forming a capacitive-current path with flying capacitors, the proposed DPSC converter alleviates both voltage and current stresses on both the inductor and switches, enhancing overall efficiency and achieving the lowest V\cdot A metric for the switches. The pro...Show More
This paper proposed an event-driven clockless level-crossing ADC (LC-ADC) suitable for biomedical applications. Thanks to the LC loop, the sampling rate of the converter automatically adapts to the input activities. Activity-dependent power consumption and data compression can thus be realized, saving system power, especially during time-sparse signal acquisition. Meanwhile, a SAR-assisted loop is...Show More
This paper presents a pseudo-pseudo-differential (PPD)--based single-OTA 2nd-order zoom ADC, which employs a 4-bit SAR conversion followed by a 2 nd-order \Delta \Sigma modulator using a single-OTA. The PPD technique significantly minimizes the OTA noise at low frequencies. A CLS-enhanced cascode inverter is proposed as the OTA, boosting its DC gain to 75dB to meet structural requirements. The c...Show More
In recent years, Gigahertz-rate oversampled CT DSMs have been consistently explored to pursue a larger bandwidth (BW) [1] –[4]. Note that the usable oversampling ratio (OSR) is seriously limited (i.e. below 10) in those works owing to the restrained clock rate. A low OSR results in poor quantization efficiency, thus limiting the achievable dynamic range (DR). In such an ultra-low-OSR context, mult...Show More
This article introduces a power-area efficient new merged capacitor switching (NMCS) scheme for successive approximation register (SAR) analog-to-digital converters (ADCs). It addresses the drawback of conventional CDAC switching schemes, where energy is consumed with each decision. In this scheme, energy is consumed during the first decision, no energy is consumed during the second decision, and ...Show More
This article presents a highly energy-efficient CT-DT pipelined noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) with a closed-loop noise-optimized two-stage dynamic amplifier working as the residue amplifier (RA). The sampling-free capacitively-coupled 1st stage breaks the kT/C limit between the SNR and the input capacitor size, thus easing the buffer r...Show More
This paper proposes a neural recording frontend with a level crossing (LC) style DR-enhancing loop, featuring fast transient response and a wide input range. A dual-Gm input stage together with a differential input single-ended output TIA is exploited, enabling energy efficient LC event detection. The LC capacitive DAC generates a voltage that follows the input, enhancing the DR. A current mode se...Show More
Low-voltage delta-sigma modulators have broad application prospects in power-constrained sensor systems but with undeveloped energy efficiency. This article includes the current development of low-voltage DSMs and the design challenges of low-voltage DT DSMs. As a case study, a DT zoom DSM with a low-voltage capacitively-biased floating inverter amplifier is presented with detailed design consider...Show More
This article presents an embedded-friendly high-precision two-step noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) designed for sensor applications. By employing a continuous-time (CT) SAR to track the input signal, the design avoids the kT/C noise typically induced by sampling operations. This approach decouples the signal-to-noise ratio (SNR) from the...Show More
This paper proposed a low-power two-stage amplifier for large capacitive load driving. A closed-loop gmboosted (CLGB) output stage is exploited to reduce the output resistance and thus makes the output pole non-dominant. This allows an internally defined dominant pole, resulting in a high gain-bandwidth (GBW) without using compensation capacitor. Meanwhile, a current-reuse stacked (CRS) slew rate ...Show More
Most noise shaping (NS) SAR ADCs still use the same control algorithm as Nyquist SAR ADC. Noticing the slow-varying input under oversampling, this paper proposed a new algorithm named quantization-error-matched RLSB-first to improve the switching efficiency. Compared with the VCM-based algorithm, the proposed algorithm saves 87.3 % switching power consumption in a 1st order NS SAR under an OSR of ...Show More
This paper presents a time-amplitude aligned level-crossing (LC) SAR ADC for sparse signal acquisition. In conventional level-crossing ADCs, misalignment between time and amplitude induces significant error during interpolation. A level-crossing SAR is first proposed in this paper to effectively cancel the misalignment. Triggered by a 16-level continuous-time LC detector, the quantization is perfo...Show More
Multiple parameter environment monitoring via wireless Internet of Thing sensors is growing rapidly, thanks to low power techniques of the node. More importantly, the ever more complex and highly efficient energy harvesting systems enable long-term continuous monitoring in inaccessible environments without needing to change the battery. This paper reviews existing energy harvesting modalities, inc...Show More
This work proposes a floating-inverter-amplifier (FIA) based high-precision dynamic zoom ADC for low-voltage battery-powered applications. A capacitive biasing technique is proposed to reboot the FIA under low voltages, which enables the FIA to operate under a near-threshold supply voltage. Furthermore, correlated-level-shifting (CLS) is employed to boost the DC gain of the FIA to 51 dB. Simulated...Show More
Deep neural networks (DNNs) can be implemented in low-power, small-area systems using compute-in-memory (CIM). This study proposes a CIM MAC macro based on 8T SRAM and a 5-bit Successive Analog-to-Digital Data Converter (SAR ADC) readout circuit to execute low-power and highspeed calculations. This architecture has no buffers between the low-power SAR ADC and the pre-stage. The SAR ADC’s capacitor...Show More
The rapid progress of smart sensors and biomedical front-ends is summoning high-precision, high-energy-efficiency ADCs. To be embedded-friendly, properties like easily driven, adaptive bandwidth, and feasible clock generation cost are also favorable. In recent years, noise-shaping (NS) SARs have gained a great vogue for their fully dynamic operation and high energy efficiency [1]–[3]. Although imp...Show More
Delta-sigma (\Delta\Sigma) analog-to-digital converters (ADCs) are well-known for oversampling and noise-shaping techniques to achieve high resolution and good power efficiency. However, free-running \Delta\Sigma ADCs are dynamic systems with memory that cannot offer one-to-one mapping between input and output samples. Therefore, incremental delta-sigma (\vert \Delta\Sigma) ADCs, resetting t...Show More
High-precision and ultra-low-power (ULP) ADCs have received significant demand recently due to their critical roles in biomedical or Internet-of-things products. However, achieving a 16-bit resolution with sub-micro-watt (< 1\mu\mathrm{W}) ADCs remains a significant challenge, serving as a bottleneck for ULP signal acquisition systems. Noise-shaping (NS) SAR ADCs can effectively reduce in-band q...Show More
This article presents a switched-capacitor (SC) delta–sigma modulator (DSM) for low-power and high-precision applications. With a 5-bit noise-shaping (NS) successive-approximation-register (NSSAR) quantizer embedded in the 2nd-order loop filter, the system achieves a stable 3rd-order noise transfer function (NTF) without coefficient scaling. Partial feedback with digital filters is adopted, which ...Show More