Realizing a neuromorphic-based artificial visual system with low-cost hardware requires a neuromorphic device that can react to light stimuli. This study introduces a photoresponsive neuron device composed of a single transistor, developed by engineering an artificial neuron that responds to light, just like retinal neurons. Neuron firing is activated primarily by electrical stimuli such as current via a well-known single transistor latch phenomenon. Its firing characteristics, represented by spiking frequency and amplitude, are additionally modulated by optical stimuli such as photons. When light is illuminated onto the neuron transistor, electron−hole pairs are generated, and they allow the neuron transistor to fire at lower firing threshold voltage. Different photoresponsive properties can be modulated by the intensity and wavelength of the light, analogous to the behavior of retinal neurons. The artificial visual system can be miniaturized because a photoresponsive neuronal function is realized without bulky components such as image sensors and extra circuits.

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In this article, we propose the wideband digital predistortion (WDPD) for a highly linear and efficient GaN HEMT Doherty power amplifier (DPA). The WDPD is composed of the memory less DPD and the memory system, which compensates for the memory effects to achieve a highly linear wideband performance. The 11th-memoryless polynomial characterizes the behavioral model of the DPA. The AM/AM and AM/PM lookup tables and the coefficients of the memory system are determined by the Recursive Least Square algorithm. For a 2-FA WCDMA signal with 10 MHz carrier spacing at 2.14 GHz, the adjacent channel leakage ratio at 610 MHz offset are improved over À50 dBc without the efficiency degradation at an output power of 36 dBm.

One prototype of the bandpass filter was fabricated on 0.8-mmthick substrate dielectric with constant r ϭ 2.65. The measured results with HP8510C are illustrated in Figure 5, as well as the simulated results with HFSS, very good agreement can be observed. The maximum pass band insertion loss is less than 1.5 dB and the in-band return losses, S11, are all less than Ϫ20 dB, even reaching Ϫ37dB at the transmission pole at 5.34 GHz. It can also be observed that the rejection band extends from 6.4 GHz to 7.8 GHz, about 20% bandwidth; the maximum rejection even reaches 50 dB, implying good potential to suppress the unwanted harmonics. CONCLUSIONSA novel bandpass filter is proposed and implemented in this letter, which is implemented with combination of two quite different electromagnetic structures-CSRR and SIW. The design strategies are discussed; one prototype was fabricated to demonstrate the validity of proposed techniques. The measured results imply good in-band behaviors with insertion loss less than 1.5 dB and good return losses all less than Ϫ20 dB. In addition, the highlight lies in the sharp out-of-band rejection; the maximum rejection almost reaches 50 dB, the stopband width is about 20% at Ϫ20 dB. plementary split ring resonators, IEEE Microwave Wireless Compon Lett 14 (2004), 280-282. 4. J. Garcia-Garcia, I. Gil, M.F. Portillo, and M. Sorolla, Equivalentcircuit models for split-ring resonators and complementary split-ring resonators coupled to planar transmission lines, IEEE Trans Microwave