Keithley 2800 WP free download

File name 2800_WP.pdf

WHITE PA P E R Why Power Meters Can't Ensure Wireless Devices Are Working Properly Introduction This paper describes the differences between the power measurements made with a power meter and those made with Keithley's Model 2800 RF Power Analyzer. For example, unlike a power meter, which uses a time domain measurement technique, the Model 2800 uses a frequency domain measurement technique. Power meters use a sensor to convert an RF waveform to a low frequency voltage, but the Model 2800 performs a frequency translation of the RF waveform, then determines RF power by digitally processing the individual frequency components of the signal. A power meter can't measure the center frequency, the power in a specific bandwidth, or the spurious power outside a specific bandwidth. Although a power meter can describe how much power is being generated, the Model 2800 can determine whether the power is being generated at the correct frequency, within the correct bandwidth, and with spurious power within acceptable limits. For testing mobile phones and RFIC power amplifiers, a power meter can't provide all the information the Model 2800 can. For example, a power meter can't verify a mobile phone or a power amplifier is transmitting at the correct channel and within the channel bandwidth, and that it isn't generating excess spurious power. In production, a power meter can pass a defective phone that's generating the correct power, but in which the power isn't contained within the appropriate channel. As a result, a power meter is inadequate for mobile phone and RFIC power amplifier testing because it can't determine whether the device is transmitting in the correct channel and if the appropriate amount of power is contained within the channel. A Model 2800, or an instrument like it, is the only type of instrument that can test a mobile phone power amplifier and transmitter properly. Keithley Instruments, Inc. 28775 Aurora Road Cleveland, Ohio 44139 (440) 248-0400 Fax: (440) 248-6168 www.keithley.com A G r e a t e r