National Semiconductor PowerWise LMH2120 power detector

A linear RMS radio frequency power detector from National Semiconductor offers up to 40 dB dynamic range.

The PowerWise LMH2120 increases wireless coverage and extends battery life for third-generation and fourth-generation mobile handsets.

It enables accurate RF power amplifier measurements, which are used to control transmit power and avoid interference with neighbouring signals.

It provides stable performance over the full temperature range of -40C to 85°C, with a temperature variation of +/- 0.5 dB over a 40 dB dynamic range at 1900 MHz, minimising guard bands.

The performance remains consistent across various modulation schemes in multimode handsets and data cards using CDMA, W-CDMA, UMTS, LTE, GSM and GPRS cellular standards.

It provides modulation-independent measurements of less than 0.3 dB, which eliminates the look-up tables required for accuracy. The device also includes a shutdown pin for reducing power consumption in between measurements to extend handset battery life.

The power detector operates from a single 2.7 to 5 V supply and provides an output voltage proportional to the RF input power in dBm. This minimises the need for extra calibration and reduces the resolution requirement for the systemÂ’s analog-to-digital converter.

It features a supply current of 2.9 mA and includes a low-power shutdown mode that reduces power consumption to 3.8 µA. It supports frequencies of 50 MHz to 6 GHz, with an RF power detection range of -35 to 5 dBm.