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Magnetotransport study has been performed on AlxGa1-xN/GaN heterostructures at low temperatures and high magnetic fields. The magneto-intersubband scattering effect of the two-dimensional electron gas (2DEG) has been observed in the triangular quantum well at the heterointerface. It is found that the effective mass of the 2DEG have strong dependence on the magnetic field and the 2DEG density due to...
Magnetotransport properties of the two-dimensional electron gas (2DEG) in the triangular quantum well at AlxGa1-xN/GaN heterointerfaces have been investigated by means of temperature dependent Shubnikov-de Haas (SdH) measurements at low temperatures and high magnetic fields under illumination. After the illumination of the heterostructures, the 2DEG concentration increases and the SdH oscillation...
This paper focuses the design of an oscillator for stable terahertz carrier generation with soliton pulses. The proposed soliton oscillator generates periodic train of ultra short-width impulses using the background noise from amplifier as an input. The oscillator is made stable with a series combination of NLTL and a unique adaptive bias controlled amplifier. A new NLTL has been designed so that...
This paper presents a robust RF front-end for 3.1-4.8-GHz direct-conversion Ultra-wideband (UWB) applications such as the MB-OFDM UWB. The circuits contain a gain controllable low-noise amplifier (LNA) with resistive feedback, a merged quadrature mixer with static current injection, and local oscillator (LO) buffers. Post-layout simulations show that the fully differential front-end achieves a maximum...
In this paper, a technique to mitigate the effect of process variations on the performances of a 1.830 GHz nano-scale CMOS LC-VCO is presented. The proposed complementary cross coupled LC-VCO, dedicated to low-power implantable RF microsystems, uses a linear voltage regulator to allow adaptive scaling of the VCO supply as a function of process parameters. The proposed VCO implementation has improved...
In this paper, a 3.24 GHz~4.56 GHz wide-band voltage-controlled oscillator (VCO) fabricated in a 0.18 ??m 1P6M CMOS process is presented. This VCO is designed with a CMOS complementary-Gm oscillator topology, features two accumulation mode MOS varactors, and body-biased pMOSs. With 1.8 V power supply, when center frequency is 3.547 GHz, the phase noise is -119.2 dBc/Hz at 1 MHz offset. The oscillation...
This paper presents a comparison study between double-switch (DS) and single-switch (SS) cross-coupled CMOS VCO architectures at 2 GHz and 16 GHz. The oscillators are designed with optimal differential tank oscillation amplitude, which is equal to the threshold voltage of the cross-coupled transistors. Measurement data from prototype oscillators show that the DS architecture can achieve a better performance...
A two-stage voltage-controlled ring oscillator is designed. Based on closed-loop system and nonlinearity analysis, oscillation start-up and oscillation frequency is predicted by poles and zeros position in s-plane. With the help of this theory analysis, a high FOM, dual tuning, differential controlled VCO is designed. Jazz 0.18 ??m CMOS technology is implemented and the layout area is 47 ??m??80 ??m...
A fully integrated voltage-controlled oscillator (VCO) for IEEE 802.11a WLAN transceivers is proposed and implemented in 0.18 μm CMOS technology with 1.8 V supply voltage. The VCO core adopts the topology of complementary cross-coupled differential inductance-capacitance (LC) tank. The VCO operates from 4.56 to 4.77 GHz with the varactor control voltage (Vtune) changing from 0.3 to 1.5 V and has a...
A wide locking range injection-locked prescaler based on CMOS ring oscillators in the 0.25-??m CMOS process is described. The prescaler??s free-running frequency is 1.47 GHz, and the locking range covers from 1 GHz to 2.4 GHz with in-phase and quadrature output. The prescaler dissipates 1.9 mA from a 3.3-V power supply.
With a simple analysis of phase noise in voltage-controlled oscillators, a 2.4 GHz CMOS LC VCO is designed in 0.18 ??m CMOS technology. The proposed VCO uses three filters to remove noise from the tail current source, the reference current source, and the output node of VCO core. The VCO has a tuning range from 2.29 GHz to 2.59 GHz, while the VCO core draws 3 mA of current from 1.8 V power supply...
In this study, the design and typical applications of an isolation feedback generator circuit were presented. The circuit was processed in 40 V SOI bipolar process technology, and integrated the precision reference source, the high-frequency oscillator, the error amplifier, and the complete modulation module, and simplified the design of the isolation and closed-loop feedback of primary switching...
This paper discusses an 8MHz square wave oscillator used for a clock signal of the digital core of a mixed signal integrated circuit (IC). The frequency is determined by a bias current that charges a capacitor until it triggers a comparator with a voltage reference as the second input. A low drop out (LDO) voltage regulator is used to supply the oscillator so that variations in the battery voltage...
A new digital pressure-sensing device is presented. It employs the Micro-ElectroMechanical Systems (MEMS) technologies to form pressure sensing using PMOS ring oscillators to generate frequency which depends on the pressure-induced stress. The digital pressure sensor has several advantages. One of them is to convert the analog measurement of pressures into the frequency measurement. Compared to a...
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