Experimental study of silicon‐based microwave switches optically driven by LEDs

Abstract

Simulated resonances were 1.104, 2.144, and 2.328 GHz, while the measured ones were 1.1, 2.1, and 2.3 GHz.In respect of radiation patterns at resonance frequencies, the simulated antenna presented maximum gains of 0.8545 dB, 2.6899 dB, and 2.3305 dB, respectively.A proof of concept using a powerharvester working at 915 MHz was conducted to get experimental radiation patterns, which at this frequency showed maximum voltage values 992 mV at 2208 on the E-plane and 1418 mV at h 5 08 on the Hplane, respectively. At 915 MHz, the simulated antenna showed a gain of 0.0784 dB at 1808 for both E-plane and H-plane and maximum radiated electric field multiplied by the radial distance of 556 mV also observed at 1808 for both E-plane and H-plane.The LPTT antenna is broadband, this ensures an impedance bandwidth of 2 GHz from 400 MHz to 2.4 GHz reference to 25 dB. The antenna performance is considerably good at its three resonance frequencies, where relatively low return losses and acceptable gains are observed. A disadvantage of this type of antenna is that if bandwidths beginning at several hundred MHz are required, this would result in a relatively large antenna. The LPTT antenna does not have high gains and low return loss as typical patches have but its main advantage is that is broadband. This antenna is applicable in low power consumption devices, battery backup or hybrid system based on both battery power and RF energy harvesting.ABSTRACT: The feasibility of utilizing small-size low-cost commercial light-emitting diodes (LEDs) to drive the optically controlled microwave switches (OCMS) is experimentally investigated. A series of experiments are performed within 0.5-5 GHz bandwidth by utilizing six kinds of LEDs and a 980 nm-laser to drive the OCMS. The results show that white, red, and violet LEDs are three competitive candidates to replace high-cost lasers as the controller of OCMS if their power density impinging on the silicon dice of the OCMS could be increased up to 100 mW=mm 2 . Additionally, the reason leading to high insertion loss of the OCMS driven by the LEDs is revealed.ABSTRACT: An InGaAs/InP three mesa double heterojunction bipolar transistor demonstrating f t /f max of 350/532 GHz was fabricated on 3 inch wafer with a 0.5 lm emitter and a composite collector. Base resistance R bb of around 19 X was achieved to sustain a relative high f max in 0.5 lm linewidth device. Small signal equivalent circuit model was established, and good agreement between measured and simulated values was achieved. Effects of some key parameters were analyzed based on simulated small signal equivalent circuit model.

The design of optically controlled phase shifter based on silicon photosensitivity

“…Many optoelectronic devices have been developed based on photosensitivity, such as photocells, photo resistors, and phototransistors . There are few studies about the effect of photosensitivity on microwave propagation …”

“…[9][10][11] There are few studies about the effect of photosensitivity on microwave propagation. [12][13][14] In this letter, a non-contacting optically controlled phase shifter is analyzed and designed. Phase shifting is realized by controlling the conductivity of semiconductor material with light illumination.…”

Microwave signal switching on a silicon photonic chip

“…Although optically controlled microwave amplitude and phase switches have attracted appreciable attention due to their superior potential performances, they are not yet sufficiently advanced for implementation in practical microwave systems. The main reasons are twofold: (i) lack of scalability and compactness due to the fact that current approaches use free-space or fiber illumination 16,17 thus requiring costly and complex packaging and (ii) the optical power level required to perform a switching operation 6,7,18–20 is prohibitively high, e.g., to achieve On/Off RF switching with extinction ratio of ~10 dB requires optical power in the range of tens to several hundreds of a milliwatts. Moreover, it should be noted that photodiode and phototransistors switches can operate at low optical power but they require electrical bias and are not scalable in large high-frequency phased array systems.…”

Optically controlled millimetre‐wave switch with stepped‐impedance lines

“…Optically controlled attenuation or switching of microwave and millimetre-wave signals has attracted increasing attention partly due to the high linearity and high isolation between signal and control circuitry [1]. Microwave switches based on illumination of silicon die bridging a microstrip or coplanar waveguide (CPW) inner conductor gap have been extensively investigated in [2][3][4][5][6]. These achieved more than 10 dB switching with either fibrecoupled lasers or infrared light-emitting diodes (LEDs) below 6 GHz, whereas the off-state isolations quickly deteriorate at higher frequencies due to increased coupling through the gap.…”

“…Moreover, Flemish and Haupt [8], Ali et al [9], and Pang et al [10] required costly and time-consuming optical lithographical fabrication and thus cannot be integrated with typical microwave printed circuit boards (PCBs) directly. In addition, none of [2][3][4][5][6][7][8][9][10] are completely absorptive (both on-state and off-state return loss (RL) ≥ 10 dB) within their operating frequency bands which may cause problems in many microwave systems such as switched antenna beamforming systems. In this paper, we report on a low-cost LED-controlled broadband photoconductive millimetre-wave absorptive switch which incorporates alternating stepped-impedance GCPW transmission lines [11,12].…”