Mean-Squared Power Detector Responds in 500 ns
Linear Technology's LT5570 provides RMS (Root-Mean-Squared) power measurement of a 40 MHz to 2.7 GHz AC signal over 60 dB dynamic range, even with a modulation crest-factor of up to 12 dB. It offers measurement accuracy of ±0.5 dB over its full dynamic range and over a temperature range of -40°C to +85°C. The device offers a full-scale rise time of 500 ns. The LT5570 provides a DC output proportional to the RMS value of the input signal power. Even if the input waveform has high crest-factor content, such as a four-carrier W-CDMA modulated waveform, its RMS conformance accuracy is typically within 0.2 dB, compared to that of a CW (continuous waveform) power. The device offers 61 dB dynamic range at 880 MHz, and 51 dB at 2.14 GHz. Its linear DC output is proportional to the input power in dBm with a scaling factor of 36.5 mV/dB, typical. Minimum sensitivity is -53 dBm at 880 MHz, and -43 dBm at 2.14 GHz. The device offers exceptional linearity, deviating less than ±0.5 dB from the ideal log-linear straight line, and over the device’s operating temperature extremes. The LT5570 operates from a single 5V supply, drawing a quiescent supply current of 26.5 mA. A shutdown feature is provided, reducing supply current to 0.1 µA. The device comes in a 10-lead 3 mm × 3 mm DFN surface mount package. Pricing starts at $5.75 each in 1,000 piece quantities.