LMH2110 Mutli-Band Power Detector Evaluation Board
Created: Oct 18, 2016
No description available.
The evolution of communication gives rise to human development, from simple smoke signals up to digital modern era of transmitting signals. Radio frequency is a band of frequency which some of these can be easily attenuated. The reference design is an evaluation board for LMH2110, which is a 45-dB logarithmic RMS power detector, suited for accurate power measurement of modulated RF signals that exhibit large peak-to-average ratios.
The reference design operates using a single power supply with a voltage range of 2.7V-5V. The LMH2110 has an RF frequency range from 50MHz to 8GHz. Banana plug P21 and P22 are the ports for the supply voltage. External power supply can applied through connector header J4. Using LMH2110 provides accurate, temperature and supply insensitive output voltage that can vary linearly to the RF input power in dBm. SMA connector P1 is assigned for the input of the RF signal. This RF signal is applied through an RF generator and is connected with a 50Ω SMA cable. The detector output can be measured via BNC connector P3. The device is active when EN pin is HIGH. The LMH2110 is designed to be used in RF applications that have a characteristic impedance of 50Ω. It has an internal 2.5V operating voltage, which means exceeding 3V on EN pin will damage the device. To prevent such overvoltage, resistor R2 and R3 forming a voltage divider is implemented. Absolute maximum ratings also can damage the LMH2110, which occur when the enable pin (EN) is switched to HIGH (from shutdown to active mode), while the supply voltage is switched off. Thus to prevent also absolute maximum ratings from happening at pin EN, resistor R1 is connected in series to limit the input current. In a transmit-power-control loop circuit, the transmit power level is insensitive to power amplifier inaccuracy, thus accuracy also of the transmit power level is dependent on the accuracy of the RF detector.
The LMH2110 can be applied also in infrastructure RF power control. Also, applications, which involve W-CDMA and LTE communication that shows large peak-to-average ratios, are best suited for the use of RMS detectors like LMH2110.