100MHz to 40GHz RMS power detector 1dB accuracy and 35dB dynamic range

     Linear Technology Corporation introduces the LTC5596, a high frequency, broadband and high dynamic range RMS power detector that provides accurate, true power measurement of RF and microwave signals independent of modulation and waveform. With an easy-to-use log-linear 29mV/dB scale response signal level of -37dbm to -2dbm, the LTC5596 delivers better than ±1dB accuracy over the entire operating temperature range and the unprecedented RF frequency range of 200MHz to 30GHz. In addition, the response of the device has a flatness of ±1dB in this frequency range. A wider frequency range of 100MHz to 40GHz is also available, although accuracy is slightly reduced at extreme frequencies. Its RF inputs are internally matched at 50Ω (from 100MHz to 40GHz), making this device extremely easy to use in any frequency band within its available frequency range.

     New 4G and 5G broadband communication systems employ high order, multi-tone OFDM modulation to achieve the higher desired data rates. Traditionally, microwave Schottky diodes have been used as detector elements. They face serious shortcomings in rectifying RF or microwave signals, and measure only the peak of the waveform, which severely distorts the actual power of the signal. In contrast, an RMS detector first performs an analog RMS calculation of the waveform and then averages the results to obtain a true power representation of the input signal, independent of modulation, carrier number, and amplitude changes. This ability to measure true power is critical for device manufacturers to set the correct transmit power to ensure maximum transmission distance and thereby improve TX range, while maintaining compliance with regulatory power limits.

     The unusually wide bandwidth of the LTC5596 allows the detector to operate seamlessly across multiple frequency bands with a common design and minimal calibration effort. For example, in backhaul microwave links below 10GHz, the LTC5596 works just as well as the 28GHz version. A single design without recalibration can result in significant cost savings for equipment manufacturers. In addition, the LTC5596's wide frequency range and improved sensitivity enable it to be used in a wide range of applications, such as radar systems, avionics, wireless infrastructure base stations, satellite communications, and test instrumentation.

     The LTC5596 operates with a single 3.3V supply and absorbs a nominal supply current of 30mA. The detector has an improved ESD protection circuit built in. All pins can withstand discharges of up to 3500V (mannequin). The device is available in two temperature classes. The Class I is designed for an operating temperature range of -40 °C to 105°C (housing). For applications prone to abnormally high temperature operating environments (e.g., high-power RF power amplifiers), a high temperature Class H version is available with a defined temperature range of -40 °C to 125°C (housing). Class H devices are fully tested 100% over the entire temperature range and are guaranteed to have strict tolerances for their slopes and intercept points, thus reducing deviations between devices. Both temperature versions are available in a 2mm x 2mm plastic 8-pin DFN package.