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Article: A 0.1 to 2.5 GHz logarithmic amplifier for RF detection. (radio frequency)(Cover Story)
- Article from:
- Microwave Journal
- Article date:
- July 1, 1998
CopyrightCOPYRIGHT 1998 Horizon House Publications, Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Logarithmic amplifiers typically are used to measure widely varying signal levels at high frequencies. These signals may vary in amplitude by 90 to 100 dB at frequencies to 3500 MHz. In addition, some log amplifiers can be used for phase demodulation by utilizing the output of the log amplifier's limiter circuit. Log amplifiers also can be used as high gain compounding amplifiers in simple demodulation schemes such as the detection of amplitude-shift keyed (ASK) signals - the log amplifier output is typically sampled by an analog-to-digital converter.
In essence, the demodulating logarithmic amplifier is an RF-to-DC converter. The log amplifier's output is a DC ...