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Full-Text Articles in Engineering

Cut Part Count And Increase Dynamic Range In The Hybrid Coupled Attenuator, Chin-Leong Lim Sep 2008

Cut Part Count And Increase Dynamic Range In The Hybrid Coupled Attenuator, Chin-Leong Lim

Chin-Leong Lim

Modern digital modulation formats are generally phase-sensitive. Therefore, the variable attenuators in digital wireless equipment should exhibit minimal phase variation over attenuation. The hybrid coupled attenuator (HCA) has substantially less phase variation than the competing constant-impedance attenuators such as the Pi and the Bridged-T. At microwave frequencies, HCA implementations tend to suffer from reduced dynamic (attenuation) range due to component parasitics, especially when plastic-packaged PIN diodes are selected to lower cost. To maximize the dynamic range in a low-cost 1.9 GHz HCA , we first identified the critical components and then compensated for their deleterious effect. This paper describes the …


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 …


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.


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 …