A Level Detector Design For Dual-Band GSM-PCS Handsets

Introduction
Schottky diode detectors are commonly used as amplitude demodulators and level detectors in wireless and other RF and microwave signal processors. Detector designs are simple to realize using low-cost, plastic packaged, silicon Schottky diodes. Figure 1 shows a simple conceptual design.

In this application note, we will review detector fundamentals and show the performance of a broadband detector that terminates a 50 Ω transmission line. Finally, a design for a level detector is presented for use in a dual-band GSM-PCS handset. This application uses the SMS7630 Zero-Bias Detector (ZBD) Schottky diode.

Schottky Detector Fundamentals

Schottky Equation
Schottky diode detector operation is based on the equation that characterizes the current-voltage relationship in a diode junction, as shown:

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•Application Note: A Level Detector Design For Dual-Band GSM-PCS Handsets