共查询到20条相似文献,搜索用时 15 毫秒
1.
The performance of traditional continuous-time (CT) delta-sigma (DeltaSigma) analog-to-digital converters (ADCs) is limited by their large sensitivity to feedback pulse-width variations caused by clock jitter in their feedback digital-to-analog converters (DACs). To mitigate that effect, we propose a modified switched-capacitor (SC) feedback DAC technique, with a variable switched series resistor (SR). The architecture has the additional benefit of reducing the typically high SC DAC output peak currents, resulting in reduced slew-rate requirements for the loop-filter integrators. A theoretical investigation is carried out which provides new insight into the synthesis of switched-capacitor with switched series resistor (SCSR) DACs with a specified reduction of the pulse-width jitter sensitivity and minimal power consumption and complexity. To demonstrate the concept and to verify the reduced pulse-width jitter sensitivity a 5 mW, 312 MHz, second order, low-pass, 1-bit, CT DeltaSigma modulator with SCSR feedback was implemented in a 1.2 V, 90 nm, RF-CMOS process. An SNR of 66.4 dB and an SNDR of 62.4 dB were measured in a 1.92 MHz bandwidth. The sensitivity to wideband clock phase noise was reduced by 30 dB compared to a traditional switched-current (SI) return-to-zero (RZ) DAC. 相似文献
2.
Sin-Jhih Li Hsieh-Hung Hsieh Liang-Hung Lu 《Microwave and Wireless Components Letters, IEEE》2009,19(10):659-661
In this letter, a multi-gigahertz phase-locked loop (PLL) with a compact low-pass filter is presented. By using a novel dual-path control in the PLL architecture, the capacitance in the loop filter can be effectively reduced for high-level integration while maintaining the required loop bandwidth. Consequently, the noise resulted from off-chip components is therefore eliminated, leading to lower timing jitter at the PLL output waveforms. In addition, the timing jitter is further suppressed due to the use of decomposed phase and frequency detection. Based on the proposed techniques, a 10 GHz PLL is implemented in 0.18 mum CMOS for demonstration. Consuming a dc power of 113 mW from a 1.8 V supply, the fabricated circuit exhibits a locking range from 10.1 to 11 GHz. At an output frequency of 10.3 GHz, the measured peak-to-peak and rms jitter are 3.78 and 0.44 ps, respectively. 相似文献
3.
《Circuits and Systems II: Express Briefs, IEEE Transactions on》2009,56(2):142-146
4.
《Solid-State Circuits, IEEE Journal of》2008,43(9):1940-1950
5.
《Solid-State Circuits, IEEE Journal of》2009,44(9):2437-2451
6.
《IEEE transactions on circuits and systems. I, Regular papers》2009,56(1):51-59
7.
Zegaoui M. Choueib N. Harari J. Decoster D. Magnin V. Wallart X. Chazelas J. 《Photonics Technology Letters, IEEE》2009,21(19):1357-1359
This letter demonstrates a 2times2 low optical crosstalk and low power consumption switching matrix device based on carrier-induced effects on an InP substrate. The matrix device comprises two digital optical switches (DOSs) with a wide multimode Y-junction associated with a sinusoidal passive integrated optical circuit with an optimized X-crossing. The passive structure was designed using a two-dimensional beam propagation method (BPM) and the entire InP-InGaAsP-InP DOS was designed using a semivectorial three-dimensional BPM. The fabricated 2times2 InP switching matrix heterostructure with lambdag=1.3 mum exhibits optical crosstalk as low as -30.5 dB for drive current of 52 mA at 1.55-mum wavelength. Maximum crosstalk change of 4 dB is measured under optical polarization variation. 相似文献
8.
《Solid-State Circuits, IEEE Journal of》2009,44(9):2426-2436
9.
《Photonics Technology Letters, IEEE》2009,21(5):334-336
10.
《Solid-State Circuits, IEEE Journal of》2009,44(2):538-548
11.
《Photonics Technology Letters, IEEE》2008,20(24):2069-2071
12.
《IEEE transactions on circuits and systems. I, Regular papers》2009,56(6):1134-1145
13.
Studies of high-speed metal-semiconductor-metal photodetector witha GaAs/AlGaAs/GaAs heterostructure
Lu J. Surridge R. Pakulski G. van Driel K. Xu J.M. 《Electron Devices, IEEE Transactions on》1993,40(6):1087-1092
A GaAs/AlGaAs/GaAs heterostructure metal-semiconductor-metal photodetector (HMSM) with an active area of 100 μm×100 μm was developed and studied. The measured risetime of the device is 30 ps. The measured falltime is as short as 23 ps. The observed ultrafast response is attributed to the reduction of both the carrier transit time and the device capacitance due to the incorporation of the AlGaAs barrier layer. The HMSM is found to have a smaller saturation capacitance and saturates at a much lower bias voltage in comparison with the conventional MSM photodetector (CMSM). At a bias of 10 V, the full width at half maximum (FWHM) of the temporal response of the HMSM is more than 20% smaller than that of the CMSM. In addition, it is found that the peak impulse response for the HMSM is substantially larger than that of the CMSM under the same operation condition. Two-dimensional and equivalent circuit analyses were carried out to interpret the observed phenomena and to provide insight into the underlying physics 相似文献
14.
《Solid-State Circuits, IEEE Journal of》2009,44(5):1510-1521
15.
Yao-Joe Yang Bo-Ting Liao 《Photonics Technology Letters, IEEE》2009,21(2):115-117
This letter presents a novel approach to realize a 4 times 4 optical switch. The optical switch consists of a micromachined silicon micromirror array and a bistable mini-actuator array. The micromirror array, which comprises vertical mirrors, cantilevers, and trenches, can be monolithically fabricated by a simple anisotropic silicon etching process in high precision and high yield. The mini-actuator array consists of 16 commercially available bistable actuators integrated with L-shape arms. The advantages of this approach include high precision, easy alignment, high fabrication yield, and low cost. Because of bistable actuation, the power consumption is very low and thus the temperature elevation of a working device is less than 0.3 K. The measured insertion losses of the four channels are between - 1.6 and - 2.3 dB. The measured crosstalk is less than -60 dB, and the measured switching time is about 13 ms. 相似文献
16.
《Microwave Theory and Techniques》2008,56(10):2356-2365
Elevation of intracranial pressure is one of the most important issues in neurosurgery and neurology in clinical practice. The prevalent techniques for measuring intracranial pressure require equipments that are wired, restricted to a hospital environment, and cause patient discomfort. A novel method for measuring the intracranial pressure is described. A wireless completely implantable device, operating at an industrial-scientific-medical band of 2.4 GHz, has been developed and tested. In-vitro and in-vivo evaluations are described to demonstrate the feasibility of microwave pressure monitoring through scalp, device integrity over a long period of time, and repeatability of pressure measurements. A distinction between an epidural and sub-dural pressure monitoring techniques is also described. Histo-pathological results obtained upon a long-term device implantation favor the utilization of the sub-dural pressure monitoring method. On the other hand, in-vivo studies illustrate a maximum pressure reading error of 0.8 mm middot Hg obtained for a sub-dural device with a capacitive microelectromechanical system sensor compared to 2 mm middot Hg obtained for an epidural device with a piezoresistive sensor. 相似文献
17.
Detector jitter, the random delay from the time a photon is incident on a single-photon-counting detector (SPD) to the time an electrical pulse is produced in response to that photon, is characterized for a number of SPDs. The jitter is modeled as a weighted sum of Gaussians. The performance in detector jitter is measured by determining the capacity of a communications channel utilizing a given detector. It is observed that the loss, measured as the ratio of the signal power required to achieve a specified capacity in the presence of jitter to that in the absence of jitter, goes as the square of the normalized jitter standard deviation (the standard deviation of the jitter in slotwidths). The loss is small when the normalized jitter is less than one, and becomes significant beyond that point. This loss must be taken into account when evaluating detectors for very high throughput channels. 相似文献
18.
We have measured the frequency response of InP/ InGaAsP/InGaAs photodiodes with separate absorption, "grading," and multiplication regions (SAGM-APD's) for a wide range (2 leq M_{0} leq 35 ) of dc gains. The results are explained in terms of a theoretical model which incorporates the transit time of carriers through the depletion region, the RC time constant, the accumulation of holes at the valence band discontinuity of the heterojunction interfaces, and the gain-bandwidth limit. 相似文献
19.
《Photonics Technology Letters, IEEE》2009,21(10):669-671
20.
A study is made of the behaviour of the small-signal base transit time of a transistor at high bias current levels, where increase of transit time occurs due to collector depletion layer contraction in combination with high level injection effects in the base. Computation of theoretical current dependence of transit time is carried out for devices of single-diffused base grading with alloyed emitter and collector junctions. A physical model of the devices, involving exponential base impurity density grading, is used as a basis of analysis. The physical parameters of this model are determined specifically for the transistor samples under study by interpretation of measured terminal properties under low-level injection conditions. Very close agreement between measured and computed dependence of base transit time on d. c. bias current is obtained, subject to appropriate allowance, in analysis, for variation of the operating temperature of the device with d. c. bias condition. 相似文献