Datasheet AD8306 (Analog Devices)

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5 MHz–400 MHz 100 dB High Precision Limiting-Logarithmic Amplifier AD8306 FEATURES FUNCTIONAL BLOCK DIAGRAM Complete, Fully Calibrated Log-Limiting IF Amplifier 100 dB Dynamic Range: –91 dBV to +9 dBV SIX STAGES TOTAL GAIN 72dB TYP GAIN 18dB Stable RSSI Scaling Over Temperature and Supplies: INHI LMHI 20 mV/dB Slope, –95 dBm Intercept 12dB 12dB 12dB LIM
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0.4 dB RSSI Linearity up to 200 MHz INLO LMLO Programmable Limiter Gain and Output Current LADR ATTEN BIAS LMDR CTRL Differential Outputs to 10 mA, 2.4 V p-p 4
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DET DET DET DET Overall Gain 90 dB, Bandwidth 400 MHz I–V VLOG Constant Phase (Typical
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56 ps Delay Skew) TEN DETECTORS SPACED 12dB FLTR Single Supply of +2.7 V to +6.5 V at 16 mA Typical Fully Differential Inputs, RIN = 1 k
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, CIN = 2.5 pF GAIN BAND-GAP SLOPE INTERCEPT 500 ns Power-Up Time, <1
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A Sleep Current ENBL BIAS REFERENCE BIAS TEMP COMP APPLICATIONS Receivers for Frequency and Phase Modulation Very Wide Range IF and RF Power Measurement Receiver Signal Strength Indication (RSSI) Low Cost Radar and Sonar Signal Processing Instrumentation: Network and Spectrum Analyzers PRODUCT DESCRIPTION
The overall dynamic range for this combination extends from The AD8306 is a complete IF limiting amplifier, providing both –91 dBV (–78 dBm at the 50 Ω level) to a maximum permissible an accurate logarithmic (decibel) measure of the input signal value of +9 dBV, using a balanced drive of antiphase inputs each of (the RSSI function) over a dynamic range of 100 dB, and a 2 V in amplitude, which would correspond to a sine wave power programmable limiter output, useful from 5 MHz to 400 MHz. of +22 dBm if the differential input were terminated in 50 Ω. Through laser trimming, the slope of the RSSI output is closely It is easy to use, requiring few external components. A single controlled to 20 mV/dB, while the intercept is set to –108 dBV supply voltage of +2.7 V to +6.5 V at 16 mA is needed, corre- (–95 dBm re 50 Ω). These scaling parameters are determined sponding to a power consumption of under 50 mW at 3 V, plus by a band-gap voltage reference and are substantially indepen- the limiter bias current, determined by the application and typi- dent of temperature and supply. The logarithmic law conform- cally 2 mA, providing a limiter gain of 90 dB when using 200 Ω ance is typically within ± 0.4 dB over the central 80 dB of this loads. A CMOS-compatible control interface can enable the range at any frequency between 10 MHz and 200 MHz, and is AD8306 within about 500 ns and disable it to a standby current degraded only slightly at 400 MHz. of under 1 µA. The RSSI response time is nominally 73 ns (10%–90%). The The six cascaded amplifier/limiter cells in the main path have a averaging time may be increased without limit by the addition of small signal gain of 12.04 dB (×4), with a –3 dB bandwidth of an external capacitor. The full output of 2.34 V at the maximum 850 MHz, providing a total gain of 72 dB. The programmable input of +9 dBV can drive any resistive load down to 50 Ω and output stage provides a further 18 dB of gain. The input is fully this interface remains stable with any value of capacitance on differential and presents a moderately high impedance (1 kΩ in the output. parallel with 2.5 pF). The input-referred noise-spectral-density, when driven from a terminated 50 Ω, source is 1.28 nV/√Hz, The AD8306 is fabricated on an advanced complementary equivalent to a noise figure of 3 dB. The sensitivity of the bipolar process using silicon-on-insulator isolation techniques AD8306 can be raised by using an input matching network. and is available in the industrial temperature range of –40°C to +85°C, in a 16-lead narrow body SO package. The AD8306 is Each of the main gain cells includes a full-wave detector. An also available for the full military temperature range of –55°C to additional four detectors, driven by a broadband attenuator, are +125°C, in a 16-lead side-brazed ceramic DIP. used to extend the top end of the dynamic range by over 48 dB. REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties
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