Systems and Communications Commons^™

Re-Design Of Precision Signal Conditioning Circuit For Detecting Schumann Resonance, Rohith Bikkina

Graduate Theses, Dissertations, and Problem Reports

Extremely low frequencies signals are waves between 3 to 30Hz and corresponding wavelengths between 10,000 to 100,000 kilometers. The specific signals used here are generated from lightning and are excited at frequencies around 8Hz, 14Hz, 20Hz. These are often called Schumann Resonance frequencies. Several stations have been built around the world for identifying ELF waves. All of those required a sparsely populated area that was far away from electric power lines because of interference from electric noise at 50 Hz and 60Hz. This project develops and tests an amplifier and filter circuit that should assist in identifying the Schumann Resonance …

Lna Integrates Fast Shutdown Function, Chin-Leong Lim

Chin-Leong Lim

To minimize dead time in time domain duplex (TDD) transceiver, reception should ideally commence as soon as transmission ends. However, the low noise amplifier (LNA), which is typically shutdown during transmission to prevent device damage and receiver overload, can exhibit a turn-on delay. In older implementations, the shutdown function is external to the LNA device. So, one way to reduce part count and to miniaturize this class of LNA is to integrate the LNA and shutdown function in a microwave monolithic integrated circuit (MMIC). The integration also allows the shutdown circuit to be connected to the LNA at an optimum …

Compact Lna Drives 2.5-Ghz Base Stations, Chin-Leong Lim

Chin-Leong Lim

Pre-Amplifiers For A 15-Tesla Magnetic Resonance Imager, Chin-Leong Lim, Peter Serano, Jerome L. Ackerman

Chin-Leong Lim

High-field magnetic resonance imagers (MRI) give better signal-to-noise ratio (SNR) and image contrast. However clinical MRIs are currently limited to 3 Tesla (T) magnetic field strength. To create an uncommon 15 T scanner for research use, we evaluated several low-cost, intended for wireless communication, GaAs enhancement-mode pseudomorphic high electron mobility transistors (ePHEMT) in the critical preamplifier slot. This paper reports the experimental results that were obtained at both module and system levels. When evaluated in our prototype 15 T scanner front-end’s preamplifier slot, the candidate devices’ sub 1dB noise figures enabled image SNR ~ 110 in a water phantom (test …

Balanced Uhf Lna Simplifies Cell Towers, Chin-Leong Lim

Chin-Leong Lim

Cellular basestations' low noise amplifiers (LNA) must have input impedances that are closely matched to the antennas. Unfortunately, the amplifier devices cannot be conjugate matched without sacrificing their noise performances. Current solutions such as the isolator and the balanced LNA can satisfactorily solve the matching problem but at the expense of increased cost, weight and size. On the other hand, the confined space atop cellular towers makes the current solutions unattractive. To shrink the balanced LNA for cellular infrastructure service, we pair a highly integrated dual-amplifier MMIC with miniature multilayer couplers. This MMIC also achieves the distinction of being the …

Balanced Amplifier Aims For Low Noise, Chin-Leong Lim

Chin-Leong Lim

Cellular basestations' low noise amplifiers (LNA) must have input impedances that are closely matched to the antennas. Unfortunately, the amplifier devices cannot be conjugate matched without sacrificing their noise performances. Current solutions such as the isolator and the balanced LNA can satisfactorily solve the matching problem but at the expense of increased cost, weight and size. On the other hand, the confined space atop cellular towers makes the current solutions unattractive. To shrink the balanced LNA for cellular infrastructure service, we pair a highly integrated dual-amplifier MMIC with miniature multilayer couplers. This MMIC also has the distinction of being the …

Low Mismatch Uhf Lna For Cellular Infrastructure, Chin-Leong Lim

Chin-Leong Lim

Cellular basestations' low noise amplifiers (LNA) must have input impedances that are closely matched to the antennas. Unfortunately, the amplifier devices cannot be conjugate matched without sacrificing their noise performances. Current solutions such as the isolator and the balanced LNA can satisfactorily solve the matching problem but at the expense of increased cost, weight and size. On the other hand, the confined space atop cellular towers makes the current solutions unattractive. To shrink the balanced LNA for cellular infrastructure service, we pair a highly integrated dual-amplifier MMIC with miniature multilayer couplers. This MMIC also achieves the distinction of being the …

Pulsed Class-G Rf Amplifier System, Kevin Maulhardt, Kevin Haskett

Electrical Engineering

No abstract provided.

Lna Lowers Noise, Raises Oip3 At 3.5 Ghz, Chin-Leong Lim

Chin-Leong Lim

A 3.5 GHz LNA with good noise figure, gain and linearity performances has been designed around a low-cost, QFN2x2-packaged monolithic integrated circuit (MMIC). Incorporation of bias regulator, ESD protection and stability network at chip-level reduces the external component count to 12. The proprietary 0.25 um EPHEMT process achieves +15-dB gain in single stage and less than 1 dB noise figure at 3.5 GHz.

Setting New Noise Performance Benchmarks Using Wideband Low-Noise High-Linearity Lnas, Chin-Leong Lim

Chin-Leong Lim

Objective: to design a 900 MHz Low-Noise Amplifier (LNA) using a MMIC fabricated on a new ultra low noise GaAs ePHEMT process. To demonstrate a new noise performance bench mark (F = 0.3 dB at IRL ≤ - 15 dB) for the plastic-packaged device class.

Material: The LNA consists of a Microwave Monolithic Integrated Circuit (MMIC) and 9 passive components mounted on a 21.5x18 mm2 Rogers RO4350 micro-strip PCB. The MMIC, which comprises a common-source amplifier and temperature-tracking active bias, is fabricated on a new GaAs ePHEMT process optimized for noise. As loss in the input matching network is proportional …

Lna Based On A Low Cost (~Usd1.30) Commercial Gaas Phemt Mmic Offers Wideband (0.4~1.4 Ghz) And Room-Temperature Low Noise (~0.3 Db) Performances That Satisfy The Ska Low Cost And No-Cooling Requirement, Chin-Leong Lim

Chin-Leong Lim

Introduction: New generations of radio telescopes such as the Square Kilometre Array consist of millions of receivers scattered over a continent. The array’s quantity and geographic considerations ruled out the traditional radio astronomy LNA implementation; i.e. costly InP devices cooled by high-maintenance closed-cycle helium (He) refrigerators. Several LNA designs have been proposed to address the cost and room-temperature operation constraints but none appear a clear winner. Peltier and package-scale cooling have also been proposed as a lower cost/maintenance alternative to He cooling but when multiplied by the quantity required can still carve a significant chunk of the budget. Additionally, cooling …

Pin Switch Protects Lna From Overloads, Chin-Leong Lim

Chin-Leong Lim

The objective of this paper is to describe how a Microwave Monolithic Integrated Circuit (MMIC) can be paired with an external PIN diode bypass switch in the implementation of a Low Noise Amplifier (LNA) with overload protection feature for mobile TV receiver applications. In the preliminary phase of the design, competing schemes for reducing LNA gain were reviewed and their respective cost-performance trade-offs were benchmarked against the customer’s set of requirements. Based on the selected design, a “proof of concept” prototype was then assembled and tested. The key components of this switch by-passable LNA were sourced from in-house product portfolio, …

Lna With A Bypass Mode Improves Overload Resistance For Mobile Tv, Chin-Leong Lim

Chin-Leong Lim

Objective: This paper describes how a Microwave Monolithic Integrated Circuit (MMIC) can be paired with an external PIN diode bypass switch in the implementation of a Low Noise Amplifier (LNA) with overload protection feature for mobile TV receiver applications.

Method: In the preliminary phase of the design, competing schemes for reducing LNA gain were reviewed and their respective cost-performance trade-offs were benchmarked against the customer’s set of requirements. Based on the selected design, a “proof of concept” prototype was then assembled and tested.

Material: The key components of this switch by-passable LNA were sourced from in-house product portfolio, consisting of …

Design And Characterization Of A 1-Watt Driver Amplifier For Wireless Infrastructure, Chin-Leong Lim

Chin-Leong Lim

Variable gain amplifiers (VGA) find application in RF systems wherever the signal amplitude must be varied in reaction to a changing environment. Transmitters' driver stage utilize VGAs to conserve power under good propagation conditions and to minimize interference to adjacent sites. Cellular base-station receivers use VGAs in the 2nd/3rd stage LNA to prevent mixer/DAC overloading. Commercially available L-band VGA devices require 14 to 19 external components and have modest linearity-to-power consumption ratio (OIP3 / Pdc). To achieve the industry's lowest component count and best linearity-to-power ratio, we developed a highly integrated VGA module from 0.25 x 3900 um enhancement-mode Pseudomorphic …

Mass-Market Designed-For-Cellular Mmics Can Be Gainfully Adapted For Use In Niche Applications On Different Frequencies, Chin-Leong Lim

Chin-Leong Lim

Due to semiconductor manufacturers’ near exclusive focus on high growth markets such as cellular and wireless data, very little commercial RND resource is expended on developing Microwave Monolithic Integrated Circuits (MMIC) for the lower-volume traditional wireless services such as aviation and land mobile, etc. To circumvent the dearth of MMICs in those under-served market segments, we intend to show how off-the-shelf cellular MMICs can be leveraged into non-cellular applications. For this purpose, a MMIC originally conceived as a 900 MHz 0.5W driver amplifier is redeployed to two dissimilar applications: (i) a high linearity Low Noise Amplifier (LNA) for the 400~520 …

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.