The MAX9930–MAX9933 low-cost, low-power logarithmic amplifiers are designed to control RF power amplifiers (PA) and transimpedance amplifiers (TIA), and to detect RF power levels. These devices are designed to operate in the 2MHz to 1.6GHz frequency range. A typical dynamic range of 45dB makes this family of logarithmic amplifiers useful in a variety of wireless and GPON fiber video applications such as transmitter power measurement, and RSSI for terminal devices. Logarithmic amplifiers provide much wider measurement range and superior accuracy to controllers based on diode detectors. Excellent temperature stability is achieved over the full operating range of -40°C to +85°C.

The choice of three different input voltage ranges eliminates the need for external attenuators, thus simplifying PA control-loop design. The logarithmic amplifier is a voltage-measuring device with a typical signal range of -58dBV to -13dBV for the MAX9930/MAX9933, -48dBV to -3dBV for the MAX9931, and -43dBV to +2dBV for the MAX9932.

The MAX9930–MAX9933 require an external coupling capacitor in series with the RF input port. These devices feature a power-on delay when coming out of shutdown, holding OUT low for approximately 2.5µs to ensure glitch-free controller output.

The MAX9930–MAX9933 family is available in an 8-pin µMAX® package. These devices consume 7mA with a 5V supply, and when powered down, the typical shutdown current is 13µA.

Applications

• RSSI for Fiber Modules, GPON-CATV Triplexors
• Low-Frequency RF OOK and ASK Applications
• Transmitter Power Measurement and Control
• TSI for Wireless Terminal Devices
• Cellular Handsets (TDMA, CDMA, GPRS, GSM)