RMS Power Detector Boasts 40-dB Dynamic Range

Sept. 21, 2010

TASKED WITH INCREASING WIRELESS COVERAGE and extending battery life for third- (3G) and fourth-generation (4G) mobile handsets, a linear root-mean-square (RMS) RF power detector supports frequencies of 50 MHz to 6 GHz with an RF power-detection range of 35 to +5 dBm. The PowerWise LMH2120 vows to enable accurate RF poweramplifier (PA) measurements. It provides stable performance from 40C to +85C with amplitude-versus-temperature variations of just 0.5 dB over a 40-dB dynamic range at 1900 MHz. The power detector operates from a single 2.7-to-5-V supply and provides an output voltage that is proportional to the RF input power (dBm). This aspect minimizes the need for extra calibration and reduces the resolution requirement for the system's analogto- digital converter (ADC). Handset designers can connect the LMH2120 to the output of the PA with a directional coupler or resistive tap. The LMH2120 consumes current of 2.9 mA and includes a low-power shutdown mode that reduces power consumption to 3 A. P&A: $2.40 each in 1000Q.

National Semiconductor
2900 Semiconductor Dr.
Santa Clara, CA 95051;
(408) 721-5000
Internet: www.national.com.

See Associated Figure

About the Author

Nancy Friedrich | Editor-in-Chief

Nancy Friedrich began her career in technical publishing in 1998. After a stint with sister publication Electronic Design as Chief Copy Editor, Nancy worked as Managing Editor of Embedded Systems Development. She then became a Technology Editor at Wireless Systems Design, an offshoot of Microwaves & RF. Nancy has called the microwave space “home” since 2005.