The rise of AI optoelectronic Sensors: from nanomaterial synthesis, device design to practical application

Power amplifiers (PAs) play an important role in wireless communications because they dominate system performance. High-linearity broadband PAs are of great value for potential use in multi-band system implementation. The purpose of this paper is to present a cascode power amplifier architecture to achieve high power and high efficiency requirements for 4.2∼5.4 GHz applications.,A common emitter (CE) configuration with a stacked common base configuration of heterojunction bipolar transistor (HBT) is used to achieve high power. T-type matching network is used as input matching network. To increase the bandwidth, the output matching networks are implemented using the two L-networks.,By using the proposed method, the stacked PA demonstrates a maximum saturated output power of 26.2 dBm, a compact chip size of 1.17 × 0.59 mm2 and a maximum power-added efficiency of 46.3 per cent. The PA shows a wideband small signal gain with less than 3 dB variation over working frequency. The saturated output power of the proposed PA is higher than 25 dBm between 4.2 and 5.4 GHz.,The technology adopted for the design of the 4.2-to-5.4 GHz stacked PA is the 2-µm gallium arsenide HBT process. Based on the proposed method, a better power performance of 3 dB improvement can be achieved as compared with the conventional CE or common-source amplifier because of high output stacking impedance.

A 4.2-to-5.4 GHz stacked GaAs HBT power amplifier for C-band applications


Purpose
High-speed Indium Phosphide (InP) HBTs have been widely used to design high-speed analog, digital and mixed-signal integrated circuits. The purpose of this study is to propose a new parameter extraction procedure for determining an improved T-topology small-signal equivalent circuit of InP heterojunction bipolar transistors (HBTs).


Design/methodology/approach
The alternating current crowding effect is considered through adding the intrinsic base capacitance in the small-signal equivalent circuit. All of the circuit parameters are extracted directly without using any approximation.


Findings
The extraction technique is more easily understood and clearer than other extraction methods, as the equations are derived from the S-parameters by peeling peripheral elements from small-signal models to get reduced ones and extracting each equivalent-circuit parameter using each equation.


Originality/value
To validate the presented parameter extraction technology, an n-p-n emitter-up InP HBT was analyzed adopting the method. Excellent agreement between measured and modeled S-parameters is obtained up to 40 GHz.


An analytic method for parameter extraction of InP HBTs small-signal model

The gamma irradiation effect in indium phosphide (InP) heterojunction bipolar transistors (HBTs) is studied in this paper. The direct-current (DC) and alternating-current (AC) characteristics are i...

Gamma-Induced Degradation Effect of InP HBTs Studied by Keysight Model

To assess the accuracy of contrast sensitivity function (CSF) in detecting dysthyroid optic neuropathy (DON) at an early stage in thyroid-associated ophthalmopathy (TAO) patients and to examine potential factors that may be linked to early visual impairments in these individuals.A total of 81 TAO patients (50 non-DON and 31 DON), and 24 control subjects participated in the study. CSF was measured with the quick CSF (qCSF) method. Optical coherence tomography angiography (OCTA) images of the ganglion cell complex layer (GCCL), superficial and deep retinal capillary plexuses (SRCP and DRCP) in a 3 mm diameter area around the macula were evaluated.Compared with the controls, the area under the log contrast sensitivity function (AULCSF) and SRCP density were significantly reduced in non-DON and DON patients (all P < 0.05). The GCCL thickness of the DON patients was thinner than that of the controls and non-DON patients (all P < 0.05). The AULCSF was significantly correlated with spherical equivalent refractive error, muscle index, SRCP density and GCCL thickness in TAO patients, respectively (all P < 0.05). However, stepwise multi-regression analysis showed that the AULCSF was only significantly correlated with SRCP density (P < 0.001). Receiver operating characteristic curve analysis showed that the AULCSF produced the most accurate discrimination between non-DON and DON patients from the controls (AUC = 0.831, 0.987, respectively; all P < 0.001).CSF change in the early stage of DON is related to SRCP density. It can be an early indicator of visual impairments associated with DON in TAO patients. 

/pdf/reduced-contrast-sensitivity-function-correlated-with-1439m8el.pdf

Reduced contrast sensitivity function correlated with superficial retinal capillary plexus impairment in early stage of dysthyroid optic neuropathy

A Watt-level Broadband Power Amplifier in GaAs HBT Process

Purpose To quantify the retinal vessel density in thyroid-associated ophthalmology (TAO) patients with visual field (VF) defect and examine its associations with mechanical and system vascular risk factors for underlying pathogenesis of VF defect in TAO. Methods The cohort was composed of 62 TAO eyes (39 with VF defect and 23 without VF defect). The pulse pressure (PP), intraocular pressure (IOP), ophthalmic rectus muscular index (MI), superficial retinal capillary plexus (SRCP), radial peripapillary capillary (RPC) density, and other related parameters were measured. The associations among these factors and VF mean deviation (MD) were analyzed. Results In TAO patients with VF defect, reduced RPC density, higher PP, and larger horizontal and vertical MI were found (all P < 0.03) when compared to TAO patients without VF defect. The RPC density was correlated with VF MD value (r = 0.242, P = 0.029), while SRCP density was not (P = 0.419). In univariable general estimating equation (GEE) analysis with RPC density as the outcome, PP and its fluctuation showed a significant association (both P < 0.04). In the final RPC model with multivariable GEE analysis, only PP (β = -0.082, P = 0.029) showed significance while PP fluctuation (P = 0.080) did not. Conclusions The elevated PP was correlated with reduced retinal peripapillary perfusion in TAO resulting in VF defect. These data suggested that the system vascular factor may be important in the pathogenesis of reduced retinal perfusion resulting in visual impairment in TAO.

/pdf/elevated-pulse-pressure-correlated-with-reduced-retinal-2oo55j59.pdf

Elevated pulse pressure correlated with reduced retinal peripapillary capillary in thyroid-associated ophthalmology with visual field defect

Purpose We explored whether thyroid-associated ophthalmopathy (TAO) patients without clinical signs of dysthyroid optic neuropathy (DON) would have a selective deficit mediated by S-cone. Methods Thirty-two TAO patients without clinical signs of DON (non-DON, 42.03 ± 9.59 years old) and 27 healthy controls (41.46 ± 6.72 years old) participated in this prospective, cross-sectional study. All observers were tested psychophysically after passing color screening tests and a comprehensive ocular examination. Isolated L-, M-, and S-cone contrast thresholds were measured at 0.5 cyc/deg using Gabor patches. We calculated the area under the receiver operating characteristic (ROC) curve to quantify the ability of chromatic contrast sensitivity to detect the early visual function changes in non-DON patients. Results S-cone contrast sensitivity in non-DON patients was found to be lower than that of healthy controls (P < 0.001), whereas the sensitivities to L- and M-cone Gabor patches were similar between these two groups (P = 0.297, 0.666, respectively). Our analysis of the ROC curve revealed that the sensitivity to S-cone had the highest index to discriminate non-DON patients from healthy controls (AUC = 0.846, P < 0.001). The deficit of S-cone was significantly correlated with muscle index in non-DON patients (R = 0.576, P = 0.001). Conclusion There is a selective S-cone deficit in the early stage of TAO. S-cone contrast sensitivity could serve as a sensitive measure of visual impairments associated with early DON in patients with TAO.

/pdf/selective-deficits-of-s-cone-in-thyroid-associated-rbghacxr.pdf

Selective deficits of S-cone in thyroid-associated ophthalmopathy patients without clinical signs of dysthyroid optic neuropathy

Bone fibrous dysplasia is a benign disease of bone tissue dysplasia. Vision impairment is the commonest neurological complication of craniofacial fibrous dysplasia. Most of the vision loss caused by craniofacial fibrous dysplasia is usually a gradual process. Very few present with acute visual impairment as described in our case.We report a patient with fibrous dysplasia presenting rapidly progressive visual loss in the left eye secondary to bone cyst formation. Transnasal endoscopic surgery guided by navigation with drainage and curettage of this bone cyst and orbital decompression resulted in progressive improvement in visual acuity that returned to normal 1 month post-operatively.In cases with acute visual loss due to fibrous dysplasia, emergency surgical treatment should be considered to preserve vision. In the surgical approach, navigation-guided nasal endoscopic surgery may be preferred because of its advantages. 

/pdf/navigation-guided-nasal-endoscopic-surgery-for-acute-vision-3an7hcqt.pdf

Hao Jin

Papers

A Watt-level Broadband Power Amplifier in GaAs HBT Process

Elevated pulse pressure correlated with reduced retinal peripapillary capillary in thyroid-associated ophthalmology with visual field defect

Selective deficits of S-cone in thyroid-associated ophthalmopathy patients without clinical signs of dysthyroid optic neuropathy

Reduced contrast sensitivity function correlated with superficial retinal capillary plexus impairment in early stage of dysthyroid optic neuropathy

Navigation-guided nasal endoscopic surgery for acute vision loss caused by fibrous dysplasia: a case report and review of literatures