Design and implementation of GM- APD array readout circuit for infrared imaging

Based on an avalanche photodiode（ APD） detecting array working in Geiger mode（ GM-APD）, a high-performance infrared sensor readout integrated circuit（ ROIC） used for infrared 3D（ three-dimensional） imaging is proposed. The system mainly consists of three functional modules, including active quenching circuit（ AQC）, time-to-digital converter（ TDC） circuit and other timing controller circuit. Each AQC and TDC circuit together constitutes the pixel circuit. Under the cooperation with other modules, the current signal generated by the GM-APD sensor is detected by the AQC, and the photon time-of-flight（ TOF） is measured and converted to a digital signal output to achieve a better noise suppression and a higher detection sensitivity by the TDC. The ROIC circuit is fabricated by the CSMC 0. 5 μm standard CMOS technology. The array size is 8 × 8, and the center distance of two adjacent cells is 100μm. The measurement results of the chip showthat the performance of the circuit is good, and the chip can achieve 1 ns time resolution with a 250 MHz reference clock, and the circuit can be used in the array structure of the infrared detection system or focal plane array（ FPA）.

Promotion of structural plasticity in area V2 of visual cortex prevents against object recognition memory deficits in aging and Alzheimer's disease rodents

Memory deficit,which is often associated with aging and many psychiatric,neurological,and neurodegenerative diseases,has been a challenging issue for treatment.Up till now,all potential drug candidates have failed to produce satisfa ctory effects.Therefore,in the search for a solution,we found that a treatment with the gene corresponding to the RGS14414protein in visual area V2,a brain area connected with brain circuits of the ventral stream and the medial temporal lobe,which is crucial for object recognition memory(ORM),can induce enhancement of ORM.In this study,we demonstrated that the same treatment with RGS14414in visual area V2,which is relatively unaffected in neurodegenerative diseases such as Alzheimer s disease,produced longlasting enhancement of ORM in young animals and prevent ORM deficits in rodent models of aging and Alzheimer’s disease.Furthermore,we found that the prevention of memory deficits was mediated through the upregulation of neuronal arbo rization and spine density,as well as an increase in brain-derived neurotrophic factor(BDNF).A knockdown of BDNF gene in RGS14414-treated aging rats and Alzheimer s disease model mice caused complete loss in the upregulation of neuronal structural plasticity and in the prevention of ORM deficits.These findings suggest that BDNF-mediated neuronal structural plasticity in area V2 is crucial in the prevention of memory deficits in RGS14414-treated rodent models of aging and Alzheimer’s disease.Therefore,our findings of RGS14414gene-mediated activation of neuronal circuits in visual area V2 have therapeutic relevance in the treatment of memory deficits.

New Active Digital Pixel Circuit for CMOS Image Sensor

A new active digital pixel circuit for CMOS image sensor is designed consisting of four components: a photo-transducer, a preamplifier, a sample & hold (S & H) circuit and an A/D converter with an inverter. It is optimized by simulation and adjustment based on 2 μm standard CMOS process. Each circuit of the components is designed with specific parameters. The simulation results of the whole pixel circuits show that the circuit has such advantages as low distortion, low power consumption, and improvement of the output performances by using an inverter.

A NOVEL AERONAUTICAL STATIC INVERTER WITH HIGH FREQUENCY PULSE DC LINK

A new combined soft switching technique and a novel topology of aeronautical static inverter with high frequency pulse dc link are proposed in this paper, namely an electrical isolated converter can realize soft switching of two stage cascade converters. It lays technical foundation for high power density, high efficiency and low cost aeronautical static inverter. The operation and design approach of this topology are carefully analyzed and studied. The validity of this topology is verified by simulation and test.

Optimum Design of Impedance Simulator for Phased Array Antnnas

The impedance of a solid state active phased array antenna varing with frequency and beam scanning scanning angle be matched with the solid state active matching network (SSAMN). In order to adjust and measure the radar conveniently and Securely, it is necessary for the impedance of the simulator of the phased array antennas to be optimized.Having selected the PIN dilde controlling circuits and the circuit parameters optimized,the simulator circuit is determined through numerical computation The experiment is given in support of the simulation.

Switchable Electromagnetic Absorber/Reflectors Using Back-Loaded Active Radio Frequency Circuits

In this paper,three switchable electromagnetic absorbers/reflectors using back-loaded active radio frequency circuits are presented.In the first design,the incident waves are received by an antenna array,transmitted to the back-loaded active circuits and then reflected into the free space when the PIN diode in series in the circuit is off.When the diode is on,the incident waves can be absorbed by a matching load.In the second design,the phase of the reflected waves in the unit cell can be manipulated by adjusting the length of the microstrip lines,allowing the reflection polarization to be tuned.In the third design,by integrating RF switching chips into the back-loaded circuits,a switchable absorber/reflector with a switching polarization state is presented.The first design is fabricated and measured.The profile of the switchable absorber/reflector is approximately 0.14.A total of 2 PIN diodes are used per unit cell for both TE and TM polarizations.By using active circuits,flat in-band reflection performance and stable absorption performance can be achieved in the frequency band of 7 to 18.5 GHz(FBW of 90%)for normal incidence,and an angular stability of 45°for TE and TM polarizations is realized.

A Mixed-Mode Biquad Employing OTAs and Grounded Capacitors

This paper introduces a mixed-mode biquad employing OTAs （operational trans-conductance amplifiers） and grounded capacitors. The circuit can perform mixed-mode operation by selecting the input and output terminals. Additionally, the circuit enables low-pass, band-pass, high-pass, band-stop and all-pass transfer functions suitably choosing the input terminals. The circuit parameters ω0 and Q can be tuned orthogonally through adjusting the trans-conductance gains of the OTAs. The biquad enjoys very low sensitivities with respect to the circuit active and passive components. The achievement examples are given together with simulation results by PSPICE.

Robust stability characterizations of active metamaterials with non-Foster loads

Active metamaterials incorporating with non-Foster elements have been considered as one of the means of overcoming inherent limitations of the passive counterparts, thus achieving broadband or gain metamaterials. However, realistic active metamaterials, especially non-Foster loaded medium, would face the challenge of the possibility of instability. Moreover,they normally appear to be time-variant and in unsteady states, which leads to the necessity of a stability method to cope with the stability issue considering the system model uncertainty. In this paper, we propose an immittance-based stability method to design a non-Foster loaded metamaterial ensuring robust stability. First, the principle of this stability method is introduced after comparing different stability criteria. Based on the equivalent system model, the stability characterization is used to give the design specifications to achieve an active metamaterial with robust stability. Finally, it is applied to the practical design of active metamaterial with non-Foster loaded loop arrays. By introducing the disturbance into the nonFoster circuit（NFC）, the worst-case model uncertainty is considered during the design, and the reliability of our proposed method is verified. This method can also be applied to other realistic design of active metamaterials.

Active quenching circuit for a InGaAs single-photon avalanche diode

We present a novel gated operation active quenching circuit （AQC）. In order to simulate the quenching circuit a complete SPICE model of a InGaAs SPAD is set up according to the I-V characteristic measurement resuits of the detector. The circuit integrated with a ROIC （readout integrated circuit） is fabricated in an CSMC 0.5 μm CMOS process and then hybrid packed with the detector. Chip measurement results show that the functionality of the circuit is correct and the performance is suitable for practical system applications.

Magnetogenetics: remote non-invasive magnetic activation of neuronal activity with a magnetoreceptor

Current neuromodulation techniques such as optogenetics and deep-brain stimulation are transforming basic and translational neuroscience. These two neuro- modulation approaches are, however, invasive since surgical implantation of an optical fiber or wire electrode is required. Here, we have invented a non-invasive magnetogenetics that combines the genetic targeting of a mag- netoreceptor with remote magnetic stimulation. The noninvasive activation of neurons was achieved by neuronal expression of an exogenous magnetoreceptor, an iron-sulfur cluster assembly protein 1 （Iscal）. In HEK-293 cells and cultured hippocampal neurons expressing this magnetoreceptor, application of an external magnetic field resulted in membrane depolarization and calcium influx in a reproducible and reversible manner, as indicated by the ultrasensitive fluorescent calcium indicator GCaMP6s.Moreover, the magnetogenetic control of neuronal activity might be dependent on the direction of the magnetic field and exhibits on-response and off-response patterns for the external magnetic field applied. The activation of this magnetoreceptor can depolarize neurons and elicit trains of action potentials, which can be triggered repetitively with a remote magnetic field in whole-cell patch-clamp recording. In transgenic Caenorhabditis elegans expressing this magnetoreceptor in myo-3-specific muscle cells or mec-4- specific neurons, application of the external magnetic field triggered muscle contraction and withdrawal behavior of the worms, indicative of magnet-dependent activation of muscle cells and touch receptor neurons, respectively. The advantages of magnetogenetics over optogenetics are its exclusive non-invasive, deep penetration, long-term continuous dosing, unlimited accessibility, spatial uniformity and relative safety. Like optogenetics that has gone through decade-long improvements, magnetogenetics, with continuous modification and maturation, will reshape the current landscape of neuromodulation toolboxes and will have a broad range of applications to basic and translational neuroscience as well as other biological sciences. We envision a new age of magnetogenetics is coming.