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Articles 151 - 166 of 166

Full-Text Articles in Electronic Devices and Semiconductor Manufacturing

Valley Splitting In Si Quantum Dots Embedded In Sige, Srikant Srinivasan Sep 2008

Valley Splitting In Si Quantum Dots Embedded In Sige, Srikant Srinivasan

Srikant Srinivasan

We examine energy spectra of Si quantum dots embedded in Si0.75Ge0.25 buffers using atomistic numerical calculations for dimensions relevant to qubit implementations. The valley degeneracy of the lowest orbital state is lifted and valley splitting fluctuates with monolayer frequency as a function of the dot thickness. For dot thicknesses ≤ 6 nm, valley splitting is found to be >150 μeV. Using the unique advantage of atomistic calculations, we analyze the effect of buffer disorder on valley splitting. Disorder in the buffer leads to the suppression of valley splitting by a factor of 2.5; the splitting fluctuates with ≈ 20 μeV …

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Design A Pin Diode Switch For High-Linearity Applications, Chin-Leong Lim Jul 2008

Design A Pin Diode Switch For High-Linearity Applications, Chin-Leong Lim

Chin-Leong Lim

This paper describes the semiconductor technology, packaging and characterization of a new PIN diode for switching WCDMA signal up to 10W. PIN semiconductor technology was picked as the basis for this switch because of the various performance and reliability advantages that can be had. A model for the PIN diode is generated based on the measured RF performance. How the various model parameters affect the RF performance is also discussed. This is followed by an application description of a 2.0 GHz switch based on the said model and a discussion of some circuit changes to further improve the performance. The …

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Rf Applications Of Pin Diodes, Chin-Leong Lim Jun 2008

Rf Applications Of Pin Diodes, Chin-Leong Lim

Chin-Leong Lim

PIN diodes are the ubiquitous "nuts & screws" components that hold together RF equipment as varied as the television, radio, 2-way radios, WLAN equipment etc. This talk covers PIN diode characteristics and RF applications such as switches, attenuators and limiters. Performance improvement techniques will also be discussed.

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Cut Loss In Low-Voltage, Wideband Pin Attenuators, Chin-Leong Lim Mar 2008

Cut Loss In Low-Voltage, Wideband Pin Attenuators, Chin-Leong Lim

Chin-Leong Lim

Many RF applications, including Cable and Satellite TV (CATV / SATV) networks, rely on voltage-variable attenuators (VVAs) for gain adjustment. VVAs consisting of PIN diodes arranged as a PI network are popular in CATV / SATV service owing to their constant impedance, high linearity, multi-decade bandwidth, low part count and compactness. When fabricated from thick bulk PIN diodes for high linearity, the PI VVA configuration typically requires a 0-15V control range. But modern equipment typically operates at 5V or less. Capping the control voltage at 5V adversely raises the VVA's minimum attenuation. To enable low voltage operation without degrading the …

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A Novel Method Of Detecting Missing Parallel/Multiple Bond-Wires In Microwave Transistors That Is Amenable To Integration With Automated Test Handlers, Chin-Leong Lim Nov 2007

A Novel Method Of Detecting Missing Parallel/Multiple Bond-Wires In Microwave Transistors That Is Amenable To Integration With Automated Test Handlers, Chin-Leong Lim

Chin-Leong Lim

A method of detecting a missing parallel-connected bond-wires in packaged microwave transistors is described. Instead of the conventional way of testing the transistor in the amplifier configuration, the new method tests the device as an oscillator. Using the oscillation frequency as the screening criterion reduces test complexity and allows easy integration with existing automated test handlers

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0.5w High Linearity Power Amplifier For Broadband Wireless (3.3 ~ 3.9 Ghz), Chin-Leong Lim Oct 2007

0.5w High Linearity Power Amplifier For Broadband Wireless (3.3 ~ 3.9 Ghz), Chin-Leong Lim

Chin-Leong Lim

This paper presents a 0.5 Watt amplifier that operates over the 3.3 ~ 3.9 GHz range. The target applications are pre-driver in base-stations and power amplifier in subscriber units. The design marries good Third Order Output Intercept Point (OIP3) and exceptional Power Added Efficiency (PAE) at IdB gain compression point (PldB). The performances are: -G = 11.8 dB, IRL & ORL < -8 dB, PldB = 28.5 dBm and OIP3 = 42.6 dBm. The superior performance is achieved through the use of Avago Technologies' proprietary 0.25um GaAs Enhancement mode pHEMT process. The device requires simple matching components to achieve wide bandwidth because of the built-in input pre-match. From the reliability standpoint, pHEMT devices are eminently suited to PA use -the drain to source resistance (RDSon) will inherently rise to counteract the thermal runaway that blights bipolar and HBT PAs. The internal bias circuit is temperature compensated and can be adjusted for either class A or class AB operation. The device is housed inside a standard 16 pin LPCC 3X3 package.

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Tackle Wideband Rf Switching With Pin Diodes, Chin-Leong Lim Jan 2007

Tackle Wideband Rf Switching With Pin Diodes, Chin-Leong Lim

Chin-Leong Lim

PIN diodes make cheaper, faster and more reliable RF switches than the mechanical competition. The two methods of constructing PIN diodes, bulk and epitaxial, result in significantly different bias current, linearity and lower frequency limit. This paper compares the wideband series switching performances of a bulk PIN diode (w = 22.5 um, Tau = 300 ns) and an epitaxial diode (w = 6.5 um, Tau = 180 ns) in similar low-cost, miniature SOD-323 packages. Through simulation and experiment, we detected significant differences in insertion loss, isolation, and third-order intercept (IP3) performances between the two diode types. In conclusion, the design …

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On-Chip Implementation Of High Speed And High Resolution Pipeline Radix 2 Fft Algorithm, Rozita Teymourzadeh, Masuri Othman Dec 2006

On-Chip Implementation Of High Speed And High Resolution Pipeline Radix 2 Fft Algorithm, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

A new on-chip implementation of Fast Fourier Transform (FFT) based on Radix 2 is presented. The pipeline and parallel approaches are combined to introduce a new high speed FFT algorithm which increases resolution by using floating point calculations in its structures. The design has the merits of low complexity and high speed performance. Furthermore, latency reduction is an important issue to implement the high speed FFT on FPGA. The proposed FFT algorithm shows the latency of (N/2 log(2) N) + 11. Moreover, this algorithm has the advantage of low mean squared error (MSE) of 0.0001 which is preferable to Radix …

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Vlsi Implementation Of High Speed And High Resolution Fft Algorithm Based On Radix 2 For Dsp Application, Nooshin Mahdavi, Rozita Teymourzadeh, Masuri Othman Dec 2006

Vlsi Implementation Of High Speed And High Resolution Fft Algorithm Based On Radix 2 For Dsp Application, Nooshin Mahdavi, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

Using Fast Fourier Transform (FFT) is indispensable in most signal processing applications. Designing an appropriate algorithm for the implementation of FFT can be efficacious in digital signal processing. Sophisticated techniques such as pipelining and parallel calculations have potential impacts on VLSI implementation of FFT algorithm. Furthermore, a mathematic approach such as floating point calculation achieves higher precision. In this paper, an efficient algorithm with using parallel and pipelining methods is proposed to implement high speed and high resolution FFT algorithm. Latency reduction is an important issue to implement the high speed FFT on FPGA. The Proposed FFT algorithm shows the …

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Diode Quad Is Foundation For Pin Diode Attenuator, Chin-Leong Lim Apr 2006

Diode Quad Is Foundation For Pin Diode Attenuator, Chin-Leong Lim

Chin-Leong Lim

Voltage-variable attenuators (VVAs) enable gain adjustment in a wide range of applications, including in cable-television (CATV), satellite-television (SATV) systems, and even test equipment and measurement systems. The PI VVA configuration using PIN diodes is ubiquitous in CATV and SATV systems owing to its low part count, small size, constant impedance, high linearity, and multi-decade bandwidth. Presently, there is a great pressure to miniaturize this VVA in order to shrink end-product size. To miniaturize this class of VVAs, we integrated four diodes into a five-pin, leadfree SOT-25 surface mount package. This paper describes the prototype VVA's design, fabrication and experimental results. …

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An Enhancement Of Decimation Process Using Fast Cascaded Integrator Comb (Cic), Rozita Teymourzadeh, Masuri Othman Dec 2005

An Enhancement Of Decimation Process Using Fast Cascaded Integrator Comb (Cic), Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

The over sampling technique has been shown to increase the SNR and is used in many high performance system such as in the ADC for audio and DAT systems. This paper presents the design of the decimation and its VLSI implementation which is the sub-component in the over sampling technique. The design of three main units in the decimation stage that is the Cascaded Integrator Comb (CIC) filter, the associated half band filters and the droop correction are also described. The Verilog HDL code in Xilinx ISE environment has been derived to describe the CIC filter properties and downloaded in …

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An Overview Of The Decimation Process And Its Vlsi Implementation, Rozita Teymourzadeh, Masuri Othman Dec 2005

An Overview Of The Decimation Process And Its Vlsi Implementation, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

Digital Decimation process plays an important task in communication system. It mostly is applied in transceiver when the frequency reduction is required. However, the decimation process for sigma delta modulator is considered in this research work. The proposed design was simulated using MATLAB software and implemented by hardware description language in Xilinx environment. Furthermore, the proposed advance arithmetic unit is applied to improve the system efficiency.

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An Improved Recursive And Non-Recursive Comb Filter For Dsp Applications, Rozita Teymourzadeh, Masuri Othman Dec 2005

An Improved Recursive And Non-Recursive Comb Filter For Dsp Applications, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

The recursive and non-recursive comb filters are commonly used as decimators for the sigma delta modulators. This paper presents the analysis and design of low power and high speed comb filters. The comparison is made between the recursive and the non-recursive comb filters with the focus on high speed and saving power consumption. Design procedures and examples are given by using Matlab and Verilog HDL for both recursive and non-recursive comb filter with emphasis on frequency response, transfer function and register width. The implementation results show that non-recursive comb filter has capability of speeding up the circuit and reducing power …

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Vlsi Implementation Of Cascaded Integrator Comb Filters For Dsp Applications, Rozita Teymourzadeh, Masuri Othman Dec 2005

Vlsi Implementation Of Cascaded Integrator Comb Filters For Dsp Applications, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

The recursive comb filters or Cascaded Integrator Comb filter (CIC) are commonly used as decimators for the sigma delta modulators. This paper presents the VLSI implementation, analysis and design of high speed CIC filters which are based on a low-pass filter. These filters are used in the signal decimation which has the effect on reducing the sampling rate. It is also chosen because its attractive property of both low power and low complexity since it dose not required a multiplier. Simulink toolbox available in Matlab software which is used to simulator and Verilog HDL coding help to verify the functionality …

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On-Chip Implementation Of Cascaded Integrated Comb Filters (Cic) For Dsp Application, Rozita Teymourzadeh, Masuri Othman Dec 2004

On-Chip Implementation Of Cascaded Integrated Comb Filters (Cic) For Dsp Application, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

This paper presents the design of a CIC filters based on a low-pass filter for reducing the sampling rate, also known as decimation process. The targeted application for the filter is in the analog to digital conversion (ADC).The CIC is chosen because of its attractive property of both low power and complexity since it dose not required multipliers. Simulink toolbox available in Matlab software is used to design and simulate the functionality of the CIC filter. This paper also shows how sample frequency is decreased by CIC filter and it can be used to give enough stop-band attenuation to prevent …

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Research Highlights, Grigory Simin Dec 1997

Research Highlights, Grigory Simin

Grigory Simin

No abstract provided.

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