Volume 42, Number 4, 2008 Print Edition

In This Issue:

2 -- Editors’ Notes
3 -- Analog Front End for 3G Femto Base Stations Brings Wireless Connectivity Home
8 -- Considering Multipliers (Part 1) [The Wit and Wisdom of Dr. Leif—7]
15 -- Design, Simulate, and Document Proprietary Wireless Systems
18 -- Tales From the Back Burner
19 -- Product Introductions

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Notch Filter Reduces Amplifier Peaking and Increases Gain Flatness

Although the ADA4817 is unity-gain stable, a high-frequency pole increases its GWP from 410 MHz at high gains to 1 GHz at unity gain, while decreasing its phase margin. Adding a discrete RLC notch filter maintains the high bandwidth and input impedance, while dramatically reducing peaking, increasing gain flatness, and reducing overshoot.

Skin Impedance Analysis Aids Active and Passive Transdermal Delivery

Pharmaceutical firms are developing alternatives to injections. Transdermal methods, which feature noninvasive delivery of medication through a patient’s skin, overcome the protective barrier in one of two ways: passive absorption and active penetration. Skin impedance analysis facilitates proper dosing.

PLC Evaluation Board Simplifies Design of Industrial Process-Control Systems

The applications for industrial process-control systems range from simple traffic control to complex electrical power grids, from environmental control systems to oil-refinery process control. The intelligence of these systems lies in their measurement and control units. The two most common computer-based systems to control machines and processes are programmable logic controllers and distributed control systems.

Reconstruct a DAC Transfer Function from its Harmonic Spectral Content

DAC output spectrums contain harmonic content due to their non-ideal transient and static behavior. This article defines a method for deriving the DAC transfer function from the observed harmonic content, assuming that the static errors, rather than the transient characteristics, are the dominant source of the distortion.

Analog Microcontroller Forms Heart of Low-Cost, High-Efficiency PA Monitor

Saving energy is crucial for efficient wireless network operation. Power amplifiers (PA), the core of base stations and repeaters, can account for more than half of their total power consumption. Monitoring and controlling the PA can: improve efficiency and reduce operating costs; maximize output power and achieve the highest possible linearity; and allow the system operator to discover problems and improve reliability.