A new switching algorithm is proposed in Successive Approximation Analog-to-Digital Converters (SA-ADCs) to reduce the power consumption in both DAC and comparator. This technique is more efficient in applications where the input signal has low-varying characteristics. For slow-varying samples, only the least significant bits of the new analog sample are extracted leading to power saving in both the capacitor-based DAC and the comparator. For an Electrocardiogram (ECG) signal and with the proposed structure, the simulated power consumption of the DAC, the comparator and the entire ADC for an 8-bit 10-kS/s converter are 74%, 38% and 52% less than those of a conventional architecture, respectively.
This paper presents a high-gain antipodal linearly tapered slot antenna (LTSA) combined with substrate integrated waveguide (SIW) technique for Ku-band applications. The effects of periodic corrugation on the radiating elements are thoroughly investigated to optimize antenna performance. The periodic corrugation contributes to higher gain as well as and lower sidelobe level. The proposed antenna demonstrates broadband performance for frequency ranges from 13GHz to over 17GHz with gain of 16dBi and relatively low cross-polarization levels of less than -25dB. The 3-dB beam-widths of 36° in the H-plane and 22° in the E-plane have been obtained.
This paper proposes an effective memory system of depth data to reduce the bandwidth requirement from the external memory for low-power 3D rendering processors. For this purpose, we propose an escape count buffer that contains information about the data size for each compressed depth block. Compared to the previous scheme, experimental results show that this approach reduces the memory bandwidth requirements up to 44%.
Fully Implantable hearing devices consist of a microphone that is implanted under the human skin. However after the implantation, the gain characteristics of the microphone are attenuated at the high frequencies because of the sound filtering effect of the skin and tissue. To solve this problems, we proposed an implantable microphone with an acoustic tube, which generates a resonance effect between the diaphragm and the acoustic transducer inside a case. By performing several experiments in water, it has been confirmed that the frequency response of the implantable microphone at high frequencies can be improved by use of the acoustic tube.
A dynamic algorithm to optimize the packet size in wireless mobile networks using Rician distribution estimation (RDE) of the mobility range is presented. The packet size adaptation algorithm is based on an estimation of the bit error rate (BER) and the dynamic link distance statistics to maximize the communication performance through automatic repeat request (ARQ). The results using the dynamically estimated probability density function (PDF) of the link distance show significant improvement in both throughput and utilization when used in rapidly changing mobile environments.
This paper presents an RFID chip for 13.56-MHz band communication fabricated on a glass substrate by using amorphous In-Ga-Zn-O thin-film transistors. Low driving-voltage logic circuits were achieved with a small Vth, a high field effect mobility of 15cm2/Vs and “active load” inverters that had small consumption currents. The RFID tag was successively driven by 13.56-MHz wireless input.
In this paper, we have compared three power gating (PG) schemes which are Single-Footer PG (SFPG), Charge-Recycled PG (CRPG), and Dual-Switch PG (DSPG), respectively, in terms of energy loss, crossover time, and wake-up time using the 45-nm Predictive Technology Model. Though the DSPG has been rarely used so far compared to the SFPG and CRPG, the comparison results tell us that the DSPG should be revisited. With the constraint of the same active speed, the DSPG shows higher energy-efficiency and faster wake-up than the others. Based on these results, the DSPG can be regarded as the most suitable PG scheme for reducing leakage and achieving fast wake-up in the future leakage-dominant VLSIs.
A low power current reused Colpitts VCO and divide-by-two circuit is proposed in 0.18µm CMOS technology. The divider is stacked on top of a common drain gm-boosted differential Colpitts VCO to share DC current. A capacitance neutralization technique is used to compensate the miller effect of the parasitic gate-drain capacitance Cgd in the VCO, and improves the generated negative resistance and phase noise performance. The Colpitts VCO works at 4.293-4.513GHz, and can provide 2.147-2.257GHz quadrature outputs through the stacked divide-by-two circuit. The VCO circuit exclude the output buffer consumes 2.8mA at 1.8V supply voltage. The measured phase noise is -109dBc/Hz at 1MHz offset frequency when the VCO output is 4.513GHz.
In this paper, for the first time, we present a small signal circuit model of quantum dot laser considering two photon modes, i.e., ground and first excited states lasing. By using the presented model, effect of temperature variations on modulation response of quantum dot laser is investigated. Simulation results of modulation response are in agreement with the numerical and experimental results reported by other researchers.
A scheme combining partial relay selection and beamforming in the dual-hop relaying system is proposed. We present the performance analysis of the scheme in Nakagami-m fading by providing closed-form expressions for the outage probability and average bit error probability as well as simple approximations for the two metrics to quantify the performance in high signal-to-noise ratio regime. In the numerical results, the correctness of the theoretical results is validated and the superior performance of the proposed scheme is also shown.