The adaptive bias technique is the common technology for improving the power-added efficiency (PAE) of the power amplifier (PA). However, the performance of the adaptive bias technique is sensitive to the frequency variation. This paper presents a novel adaptive bias as the common-source bias of the 45–2500 MHz CMOS PA, which combines the subthreshold PD to decrease the effect on frequency of adaptive bias technique and a unity gain amplifier to increase the detection sensitivity, for improving the PAE at back-off mode over the wide bandwidth. The proposed PA provides a good performance from 45 MHz to 2500 MHz, while the peak of the saturation output power is 24.02 dBm over the frequency band. Moreover, the maximum PAE achieves 44.61% at 500 MHz and the PAE is larger than 28.48% at 3 dB back-off power. The chip size of the broadband PA achieves 1.87 mm2 at TSMC 0.18 um technology process. It draws 200 mA from 3.3 V supply voltage.
Isolation is one of the most important electric characteristics in a compact MIMO (multiple-input and multiple-output) system. Fragment-type structure receives much attention for acquiring high isolation due to its novel topology structure. In this paper, several novel boundary-based weighted sum filtering operators are proposed to obtain fragment-type isolation structure designs. Experiments on the isolation structure design of a compact MIMO PIFAs (planar inverted-F antennas) system are investigated. Comparison results show that the proposed hybrid filtering matrices could generate smoother structure, thus obtain wider impedance bandwidth and better radiation efficiency.
This paper presents a synchronous rectified (SR) flyback AC-DC converter based on capacitor-coupled isolated communication. Instead of bulky opto-couples as isolators, the proposed converter integrates an isolated capacitor to accomplish communication between the primary and secondary side, in an attempt to reduce system size. In secondary side, an adaptive zero-current detector (ZCD) for driving synchronous rectifier is adopted to increase efficiency. The converter is designed and fabricated in a 0.18-µm BCD process. The experimental results demonstrate that our scheme shrinks the isolator size by a factor of 52.24 times and simultaneously improves the system efficiency by 3% with ZCD.
Read disturb is a circuit-level noise in SSDs, which may corrupt existing data in SSD blocks, and then results in high read error rate and longer read latency. This paper proposes schemes of write scheduling and data reallocation, by taking account of read disturb. We first construct a model to estimate the block read error rate caused by read disturb, by referring the factors of block’s P/E cycle and the accumulated read count to the block. Then, the data being intensively read are flushed to the block having a small read error rate. Moreover, we introduce a data reallocation mechanism, which is completed by read reclaim, for balancing read accesses in all blocks. Thus, the total read errors introduced by read disturb can be cut down. Through a series of emulation tests based on several realistic disk traces, we demonstrate that the proposed mechanism can yield attractive performance improvements on the metrics of read latency and read error rate.
A phased array system with quasi-hemispherical region scanning performance is proposed. The proposed system is implemented using triangular substrate integrated waveguide (SIW) elements with short ends, which have a quasi-hemispherical beam pattern. Shorted vias at the vertex and side of the triangular patch were made to act as SIW antennas, generating magnetic currents characterized by radiating to a quasi-hemisphere pattern. The measured results show that the prototype planar phased array has scanning ranges of about 160° in both horizontal and vertical planes, and about 170° in both two diagonal direction planes, with 5 dB gain fluctuation.
To enhance the vital sign radar’s detection accuracy of heartbeat rate (HR), which is heavily affected by the harmonics of respiration frequency, this paper proposes a waveform-driven matched filtering method based on polynomial fitting extraction. The merit of this approach lies in that, the quasi-ideal matching impulse approximating the actual heartbeat signal can be readily retrieved by subtracting the polynomial fitted waveform from a received signal, which provides high adaptability for individual subjects. Essentially, this extraction greatly removes the harmonic interference originated from respiration, thus considerably improving the HR detection accuracy. Simulations are performed to acquire the proper fitting order and the effective impulse duration. Guided by these two parameters, a 10-GHz non-contact continuous-wave (CW) Doppler radar system with typical microwave laboratory instruments is constructed. Experimental results confirmed the effectiveness of the proposed method, showing that the average errors of HR can be reduced from 46.21% to 0.96% under different subjects and distances, and from 38.05% to 0.90% in continuous measurement for one subject.
Vision measurement has encountered the bottlenecks in capturing and processing the images of laser spots under harsh working environment of strong sunshine and complex background. Breaking through the camera calibration, we propose that the corresponding relationship between pixel coordinates of laser spots, but not the camera, and measurement distances generated from laser rangefinder is directly calibrated under good working environment. The pixel coordinates of laser spots can be obtained from the calibration model and measurement distances during practical measurement. The imaging of laser spots by camera is no longer needed. Experimental results demonstrate that the measurement errors are in the millimeter level within 20 m distance outdoors.