Majlesi Journal of Telecommunication Devices
Volume:4 Issue: 4, Dec 2015

In this paper, a new topology of Gilbert mixer with improved power consumption using the CMOS 0.18μm TSMC RF design kit is proposed. The proposed mixer is a down conversion one working in 2.4GHzradio frequency (RF), with a 2.5GHz local oscillator (LO) and a 100MHz intermediate frequency (IF). The circuit of this mixer is based on a low power differential transconductor in RF stage, wherein the ac and dc current paths through the source degeneration resistors and dc bias are isolated from each other. The supply is 1.8Vdc and the obtained power consumption is as low as 1mW.

A hybrid TDM/WDM PON network with 64 users was designed by a bidirectional optical fiber in this paper. Having analyzed the performance of the hybrid network with regard to the importance of photodetectors as the first receiving block, the performance of photodetectors PON and APN for different fiber lengths are compared. All designing procedures were performed by optisystem software and measured values were represented and evaluated. As expected, the result showed that, due to an increase in the length of the fiber, the amount of noise increased and consequently, the signal to noise ratio decreased. However, it was found that the used topology was able to receive information in both upstream and downstream for fibers with a length up to 30 km and parameters of Q factor, the bit error ratio, and the signal to noise ratio are desired and acceptable for fibers of 30 km length. In addition, the values of simulations show that the performance of APD diode and the Q factor and BER obtained from APD is better than that of PIN which could be expected because APD is more sensitive than PIN.

This paper proposes and simulates a fourth order single-loop modulator with feed forward structure which covers the ADSL-standard bandwidth. Design of this modulator employs a low distortion structure suitable to target bandwidth to achieve its objectives. To achieve the required specifications of target standard, a fourth order modulator with oversampling rate of 14, bandwidth of 1.2 KHZ, SNR of 87 dB, and accuracy of 14.2 bits is designed and simulated. Block diagram of the proposed structure is also presented

In this paper, a low-power ultra wideband (UWB) low-noise amplifier (LNA) with high and flat gain is proposed. By using an input common-gate stage, an input matching from 3.1 to 10.6 GHz is achieved. The output matching is obtained by using the output matching network including output buffer, capacitor and inductor. In proposed LNA, current-reused technique is adopted in order to reduce the power dissipation. The proposed LNA provides high gain with excellent flatness and low noise figure over the broadband while it has very good stability too. The LNA was simulated with a TSMC 0.18-µm CMOS technology. The input and output reflection coefficients are less than -11 dB from 3 to 11GHz and -10 from 2.3 to 12 GHz, respectively. The noise figure of the proposed LNA remained under 4.3 dB from 2.2 to 10.7 GHz with minimum value of 3.12 dB. Additionally, high and flat gain of 13±1.8 dB is achieved for whole the ultra band. The linearity of input third-order intercept point is -7.76 dBm and P-1dB compression is -17 dBm. The power consumption at 1.5-V supply voltage without an output buffer is only 11 mW.

In this article, we have given the size of the coupling constant, a system of quantum electro-dynamics in weak coupling regime, strong and very strong case our analysis and simulation. Also by choosing the type of quantum system and the electrical field of the electromagnetic wave, the size of Rabi frequency to the extent that we are less than excited states and photons in the cavity decay rate is. In this case, the interaction between the quantum system and electromagnetic field coupling regime is weak. It is one of the properties of quantum light emitting modes of the cavity modes can be in resonance with each other, resulting in a sudden increase in the spontaneous emission rate, causing a sharp peak in the density of the spontaneous emission spectrum. The nature of this regime leads to appropriate in light production applications, such as it is possible to increase efficiency, reduce the threshold lasers emitting light in alignment with the vertical cavity structure light emitting diodes noted. Also property is listed under the regime of entangled photons is used in the production of instant. While this research, the rotating wave approximation is used in this context, survival and annihilation operators of photons Sinusoidal behavior.

The structure of an optical communication system similar to any other electrical connection system consists of several elements, including the transmitter (light source), medium (fiber optic) and receiver (optical detector) is. Standard single-mode fibers for data transmission at wavelengths normally used 33/1 micrometers and 55.1 micrometers. Optical fibers in the wavelength range of the losses are insignificant. Despite the low loss optical fibers for data transmission over long distances (more than 50 km), the need to strengthen our optical pulses again. Therefore, the optical amplifiers are required. Semiconductor optical amplifier polarization is sensitive to the structure used to relieve tension. The advantages of optical communication devices compared to other communication devices, such as bandwidth, low weight, low-loss optical fiber, flexibility, safety data sent against electromagnetic interference and inexpensive noted.