50 MHz, 80 dB Demodulating a Logarithmic Amplifier with Limiter Output AD606 a loadable output voltage of +0.1 V dc to +4 V dc. The logarith- FEATURES mic scaling is such that the output is +0.5 V for a sinusoidal Logarithmic Amplifier Performance input of 75 dBm and +3.5 V at an input of +5 dBm over this 75 dBm to +5 dBm Dynamic Range range the logarithmic linearity is typically within 0.4 dB. All 1.5 nV/ Hz Input Noise scaling parameters are proportional to the supply voltage. Usable to >50 MHz 37.5 mV/dB Voltage Output The AD606 can operate above and below these limits, with On-Chip Low-Pass Output Filter reduced linearity, to provide as much as 90 dB of conversion Limiter Performance range. A second low-pass filter automatically nulls the input 61 dB Output Flatness over 80 dB Range offset of the first stage down to the submicrovolt level. Adding 638 Phase Stability at 10.7 MHz over 80 dB Range external capacitors to both filters allows operation at input fre- Adjustable Output Amplitude quencies as low as a few hertz. Low Power The AD606s limiter output provides a hard-limited signal +5 V Single Supply Operation output as a differential current of 1.2 mA from open-collector 65 mW Typical Power Consumption outputs. In a typical application, both of these outputs are CMOS-Compatible Power-Down to 325 mW typ loaded by 200 W resistors to provide a voltage gain of more than <5 ms Enable/Disable Time 90 dB from the input. Transition times are 1.5 ns, and the APPLICATIONS phase is stable to within 3 at 10.7 MHz for signals from Ultrasound and Sonar Processing 75 dBm to +5 dBm. Phase-Stable Limiting Amplifier to 100 MHz The logarithmic amplifier operates from a single +5 V supply Received Signal Strength Indicator (RSSI) and typically consumes 65 mW. It is enabled by a CMOS logic Wide Range Signal and Power Measurement level voltage input, with a response time of <5 m s. When dis- abled, the standby power is reduced to <1 mW within 5 m s. PRODUCT DESCRIPTION The AD606J is specified for the commercial temperature range The AD606 is a complete, monolithic logarithmic amplifier of 0 C to +70 C and is available in 16-lead plastic DIPs or using a 9-stage successive-detection technique. It provides SOICs. Consult the factory for other packages and temperature both logarithmic and limited outputs. The logarithmic output is ranges. from a three-pole post-demodulation low-pass filter and provides FUNCTIONAL BLOCK DIAGRAM INHI COMM PRUP VPOS FIL1 FIL2 LADJ LMHI 16 15 14 13 12 11 10 9 REFERENCE AND POWER-UP 30pF 360kV X1 360kV 30pF 30kV 30kV OFFSET-NULL LOW-PASS FILTER 1.5kV FINAL MAIN SIGNAL PATH LIMITER 11.15dB/STAGE 250V 9.375kV 12mA/dB 2pF TWO-POLE HIGH-END 1.5kV SALLEN-KEY DETECTORS FILTER 9.375kV ONE-POLE X2 FILTER AD606 2pF 2mA/dB 12 345 67 8 INLO COMM ISUM ILOG BFIN VLOG OPCM LMLO REV. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties Tel: 781/329-4700 World Wide Web Site: ( T = +258C and supply = +5 V unless otherwise noted dBm assumes 50 V) AD606SPECIFICATIONS A Model AD606J Parameter Conditions Min Typ Max Units SIGNAL INPUT Log Amp f AC Coupled Sinusoidal Input 50 MHz MAX Limiter f AC Coupled Sinusoidal Input 100 MHz MAX Dynamic Range 80 dB Input Resistance Differential Input 500 2,500 W Input Capacitance Differential Input 2 pF SIGNAL OUTPUT Limiter Flatness 75 dBm to +5 dBm Input Signal at 10.7 MHz 1.5 +1.5 dB With Pin 9 to V via a 200 W Resistor POS and Pin 8 to V via a 200 W Resistor POS Output Current At Pins 8 or 9, Proportional to V , LADJ Grounded 1.2 mA POS LADJ Open Circuited 0.48 mA Phase Variation with Input Level 75 dBm to +5 dBm Input Signal at 10.7 MHz 3 Degrees LOG (RSSI) OUTPUT )/dB 37.5 mV/dB Nominal Slope At 10.7 MHz (0.0075 V POS At 45 MHz 35 mV/dB Slope Accuracy Untrimmed at 10.7 MHz 15 5 +15 % 88.33 dBm Intercept Sinusoidal Input Independent of V POS Logarithmic Conformance 75 dBm to +5 dBm Input Signal at 10.7 MHz 1.5 0.4 +1.5 dB Nominal Output Input Level = 75 dBm 0.5 V Input Level = 35 dBm 2 V Input Level = +5 dBm 3.5 V Accuracy over Temperature After Calibration at 35 dBm at 10.7 MHz 3 +3 dB to T T MIN MAX Video Response Time From Onset of Input Signal Until Output Reaches 400 ns 95% of Final Value POWER-DOWN INTERFACE Power-Up Response Time Time Delay Following HI Transition Until 3.5 m s Device Meets Full Specifications AC Coupled with 100 pF Coupling Capacitors Input Bias Current Logical HI Input (See Figure 12) 1 nA Logical LO Input 4 m A POWER SUPPLY Operating Range 4.5 5.5 V Powered-Up Current Zero Signal Input 13 mA T to T 13 20 mA MIN MAX Powered-Down Current T to T 65 200 m A MIN MAX Specifications subject to change without notice. 2 REV. B