A low phase noise and low power 3–5 GHz frequency synthesizer in 0.18 µm CMOS technology

A low power frequency synthesizer for WLAN applications is proposed in this paper. The NMOS transistor-feedback voltage controlled oscillator (VCO) is designed for the purpose of decreasing phase noise. TSPC frequency divider is designed for widening the frequency range with keeping low the power consumption. The phase frequency detector (PFD) with XOR delay cell is designed to have the low blind and dead zone, also for neutralizing the charge pump (CP) output currents; the high gain operational amplifier and miller capacitors are applied to the circuit. The frequency synthesizer is simulated in 0.18 µm CMOS technology while it works at 1.8 V supply voltage. The VCO has a phase noise of −136 dBc/Hz at 1 MHz offset. It has 10.2% tuning range. With existence of a frequency divider in the frequency synthesizer loop the output frequency of the VCO can be divided into the maximum ratio of 18. It is considered that the power consumption of the frequency synthesizer is 4 mW and the chip area is 10,400 µm².     

Prediction of Conditions for Chloride–Hydride Epitaxy of Ga1 – yInyAs1 – xPx Layers Isoperiodic with GaAs and GaAs1 – xPx

Semiconductors - For obtaining multicomponent III–V solid solutions, the vapor-phase methods such as the chloride–hydride epitaxy, the epitaxy from organometallic compounds, and the...     

Stimulated and spontaneous emission of Cd<Subscript>x</Subscript>Hg<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Te structures in the range 3.2–3.7 µm at 77 K

Stimulated emission of radiation from Cd_xHg_1?xTe samples pumped by a Nd:YAG laser at temperature T≈77 K is obtained. Both spontaneous and stimulated emission is observed for the wavelengths λ in the range 3300–3600 nm. Experimental emission spectra are presented. The special features of the spectra and the possible applications of the structures are discussed.     

Tandem small molecule organic photovoltaic cells with broad spectral response up to 1 μm and a high open-circuit voltage

We report a series-connected small molecule tandem photovoltaic cell utilizing two donors with complementary photovoltaic characteristics, lead phthalocyanine (PbPc) in the front subcell and boron subphthalocyanine chloride (SubPc) in the back subcell, to achieve both near infrared (NIR) response up to 1 μm and high open-circuit voltage (V_OC) of more than 1.5 V in the same device. We find that the C₆₀ layer thickness in the front subcell has a critical impact on the overall optical structure and photovoltaic performance of the tandem device. By combining transfer matrix calculations with subcell-selective spectral measurements, we are able to tune the optical field distribution inside the active layers and increase the photocurrent outputs from both subcells, leading to EQE > 30% over the wavelength range 400 nm < λ < 900 nm. This optimized tandem cell exhibits J_SC = (5.5 ± 0.1) mA/cm², fill factor = 0.54, V_OC = 1.53 V, and a power conversion efficiency of (4.5 ± 0.2)%.