High-performance RF power detector simultaneously delivers rms and envelope outputs

NORWOOD, USA: Analog Devices Inc. (ADI) has introduced a new highly integrated, high-performance RF detector for use in wireless, instrumentation, defense, and other broadband applications.

ADI’s new ADL5511 TruPwr rms (root mean square) and envelope detector (an electronic circuit that takes a RF signal as input and provides an output that represents the envelope of the signal) offers a high level of integration and functionality by combining two RF functions into one small chip, thereby simplifying designs and reducing BOM (bill of materials) cost.

Improving the PAE (power added efficiency) of high-powered amplifiers continues to be a challenge for wireless and broadband equipment manufacturers. Next-generation WiMAX systems and LTE mobile data and voice systems are adopting OFDM (orthogonal frequency division multiplexed) modulation that supports a large number of subcarriers.

The high peak-to-average ratio of these modulated signals causes PAs (power amplifiers) to be backed off from their maximum transmit powers significantly, thereby making the PA less efficient. To improve PA efficiency, an envelope detector has become increasing popular.

In drain modulation architectures, an envelope detector modulates the PA power supply from the incoming RF signal, thereby only giving the PA the power needed to properly transmit the RF signal. Traditional architectures leave the PA biased at a much higher power level in order to ensure the PA can properly transmit peak power, but are not capable of reducing PA bias when transmitting lower RF power.