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Xiong Zhou - IEEE Xplore Author Profile

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This article presents a digital readout integrated circuit (DROIC) with fully ON-chip image algorithm calibration based on the pixel-level 18-bit analog-to-digital converter (ADC) for infrared focal plane array (IRFPA) applications. Such ON-chip calibrations include bad pixel compensation, nonuniformity correction, and background subtraction, which are implemented to avoid ON-chip memory storage f...Show More
This brief presents an analytical treatment of the initial motional current ${i}_{m}{(}{0}{)}$ of the Pierce crystal oscillator (XO), which is critical for determining its start-up time ${T}_{s}$ . Specifically, the limitation of energy injection to boost ${i}_{m}{(}{0}{)}$ is studied, and the dc-settling process (DCS) at the dawn of the start-up for stimulating ${i}_{m}{(}{0}{)}$ is shown....Show More
This paper presents a low power, low phase noise, and small chip area transformer-based PMOS-only stacked-g», LC VCO in a 28-nm process. Both the top and bottom use PMOS cross-coupled pairs to provide negative resistances with suppressing the flicker noise. An interleaved transformer is used to get a higher coupling coefficient to achieve small chip area and high passive voltage gain. The VCO exhi...Show More
This paper presents a mismatch error cancellation technique for high-resolution successive approximation register (SAR) analog-to-digital converter (ADC). The proposed technique that combines residue voltage oversampling and capacitors rotation significantly diminishes the impact of capacitor mismatch without calibration. A VCO-based comparator is adopted to achieve good noise performance with hig...Show More
For a multichannel bio-potential signal acquisition front-end, it's total CMRR (TCMRR) is restricted by these three factors: the inherent CMRR (ICMRR) of the amplifier used in the acquisition front-end, the impedance mismatch of electrodes, and the systematic mismatch due to the shared reference electrode. This paper presents a 8-channel bio-potential front-end with multi-channel common-mode repli...Show More
An accurate performance evaluation of jitter-power figure-of-merit (FOM) for multiplying delay-locked loop (MDLL) is presented. For a typical MDLL employing a single-ended multiplying-delay ring voltage-controlled oscillator (MDVCO), it can be tuned via the capacitive loads to uphold a constant normalized phase noise (PN) across different frequencies for better jitter-power performance. Linear app...Show More
This article discusses the on-chip measurement of the power-supply noise (PSN) and demonstrates a scalable PSN spectrum analyzer with significantly improved speed and accuracy. Compressed sensing is exploited in the autocovariance-based measurement since the cyclostationary PSN is sparse. A six-level voltage-controlled oscillator (VCO)-based phase quantizer is proposed to improve the noise perform...Show More
High common-mode rejection ratio (CMRR) of an analog front end (AFE) requires high intrinsic CMRR of the front-end amplifier with high input common-mode (CM) impedance. This article presents a common-mode replication (CM-REP) technique, which replicates the input CM voltage over the front-end amplifier. By eliminating the CM current flow and its mismatch effect, CM-REP improves CMRR and input CM i...Show More
A low power and high-speed sample-and-hold (S/H) circuit which is suitable for the 16bit pipelined analog-to-digital converter (ADC) is proposed. By using the dynamic bias technique, The OTA in the S/H is realized with lower power dissipation. This S/H is fabricated in $0.18\ \mu\ \mathrm{m}$ mixed signal CMOS process and occupies 0.128mm2. It is integrated in a 16bit 25MS/s pipelined ADC which de...Show More
This paper presents a comparator speed enhancement technique for successive approximation register (SAR) analog-to-digital converter (ADC) under near- and sub-threshold supply voltages. The proposed delayed cross-coupling comparator effectively improves the speed of the comparator while maintaining a good noise performance. This work has been proved by a 350mV 8bit 12MS/s SAR ADC designed in a 65n...Show More
A 128-kHz RC time-constant-based relaxation oscillator is designed in 180-nm CMOS for ultra-low-power applications. The chopping structure and replica path delay loop are employed in this work to eliminate the effect of comparator offset and path delay respectively, leading to a frequency accuracy of ±0.21% over the temperature range from -20°C to 100 °C. The power consumption is 344 nW with 0.8-V...Show More
Infrared focal plane arrays (IRFPAs) have been widely used in industrial, scientifical and medical imaging applications [1]–[5]. Due to the limitation of the manufacturing process, material quality and other factors, IRFPAs inevitably suffer from the current non-uniformity under the same light intensity; and the bad pixel with extreme photoelectric response which significantly degrade the quality ...Show More
In this work, a 10b 400MS/s single-channel SAR ADC is reported. Without an auxiliary sub-ADC, a subranging architecture is proposed, where only one comparator is used with the subsetted capacitive DAC (CDAC), eliminating the mismatch of comparators and saving area. For the subranging process, a partial detect-and-skip (PDAS) switching scheme is proposed, which improves both power efficiency and li...Show More
This paper presents a sampling speed-enhancement technique for SAR ADCs under near-threshold supply voltages. The proposed level-shifted boosting circuit generates sharp falling edges for the sampling clock, which is found a key factor limiting the sample speed under ultra-low voltages. A 0.35V 8b 12MS/s SAR ADC is designed in a 65nm CMOS technology to prove this technique. The post-layout simulat...Show More
This paper presents the sampling and comparator speed-enhancement techniques for SAR ADCs under near-threshold supply voltages. The proposed level-shifted boosting circuit generates sharp falling edges for the sampling clock, which is found a key factor limiting the sample speed under ultra-low voltages. Delayed cross-coupling comparator is introduced in this work, which enhances the comparator re...Show More
High common-mode rejection ratio (CMRR) with concurrent electrode offset rejection is essential for physiological signal acquisitions. This article presents a CMRR enhancement technique for ac-coupled instrumentation amplifiers (ACIAs), where the mismatch of passive components limits the CMRR performance primarily. A modified chopping structure is proposed to mitigate the mismatch effect of the ps...Show More
This work presents a fully integrated PSN analyzer with significantly improved measurement speed and noise performance. Compressed sensing is exploited due to the sparse nature of PSN signals. A VCO-based muiti-level phase quantizer is proposed, offering improved noise performance. A polyphase clock generator is also implemented on chip, enabling the whole system to work with only one external clo...Show More
Interfacing with high-impedance sensors, such as dry-contacted electrodes and accelerometers requires high CMRR with sufficient input impedance concurrently. From the system point of view, the total CMRR (TCMRR) is determined by the intrinsic CMRR (ICMRR) of the front-end amplifier as well as the imbalance of source impedance; the latter has to be accommodated by large input common-mode (CM) imped...Show More
This article presents a 14-bit 4-MS/s voltage-controlled oscillator (VCO)-based successive approximation register (SAR) analog-to-digital converter (ADC), where the metastability of the VCO-based comparator is exploited for the background calibration of mismatch errors. A closed-form behavioral analysis of VCO-based comparators has been studied in the presence of noise, showing that the metastabil...Show More
This paper presents a multi-slice VCO-based quantizer (MSVQ) for high-resolution power supply noise analysis. To relax the trade-off between accuracy and measurement time, a multi-slice quantizer at a relatively higher sampling rate is proposed, and the auto-covariance replaces the autocorrelation to obtain PSD while immunes the spurs introduced by the quantizers itself and further reduces noise f...Show More
A new type of quantizer with build-in weighted summation function is proposed for replacing summer in feedforward delta sigma modulators. To verify the validity, a 2nd-order 8-level modulator based on this quantizer has been implemented in 180 nm CMOS technology. Simulation results show that the modulator achieves a 99.2 dB SNDR in 25 kHz bandwidth while consumes 1.56 mW under 1.8 V supply.Show More
This paper presents the design and demonstration of a 5-bit Ka-band phase shifter with amplifiers to compensate for the passive loss using a 0.13-μm SiGe BiCMOS technology. Adopting the switched low-pass (LP)/high-pass (HP) networks in the phase shift stages, the phase shifter exhibits measured RMS phase and gain errors less than 4° and 0.6 dB, respectively, within the frequency range of 30-40 GHz...Show More
This paper presents a 12-bit asynchronous successive approximation register (SAR) analog-to-digital converter (ADC) implemented in 40nm CMOS technology. A VCO-based comparator is employed to adjust the noise level adaptively and its oscillation number is harnessed to bypass unnecessary cycles for saving energy. A 1-bit split-and-recombination redundancy and a digital error correction for bypass lo...Show More
Subthreshold amplifiers suffer from the limited voltage headroom which leaves little space for conventional analog techniques to enhance performance and efficiency. This paper presents an evolution process of implementing conventional structures with inverters, allowing ultralow-voltage operation with increased flexibility in adopting traditional circuit techniques. Based on the proposed inverter-...Show More
A successive approximation register (SAR) analog-to-digital converter (ADC) with a voltage-controlled oscillator (VCO)-based comparator is presented in this paper. The relationship between the input voltage and the number of oscillation cycles (NOC) to reach a VCO-comparator decision is explored, implying an inherent coarse quantization in parallel with the normal comparison. The NOC as a design p...Show More