AD603:  Low Noise, 90 MHz Variable Gain Amplifier

The AD603 is a low noise, voltage-controlled amplifier for use in RF and IF AGC systems. It provides accurate, pin-selectable gains of −11 dB to +31 dB with a bandwidth of 90 MHz or +9 dB to 51+ dB ...More

AD603:  Low Noise, 90 MHz Variable Gain Amplifier

Product Description

The AD603 is a low noise, voltage-controlled amplifier for use in RF and IF AGC systems. It provides accurate, pin-selectable gains of −11 dB to +31 dB with a bandwidth of 90 MHz or +9 dB to 51+ dB with a bandwidth of 9 MHz. Any intermediate gain range may be arranged using one external resistor. The input referred noise spectral density is only 1.3 nV/√Hz, and power consumption is 125 mW at the recommended ±5 V supplies.

The decibel gain is linear in dB, accurately calibrated, and stable over temperature and supply. The gain is controlled at a high impedance (50 MΩ), low bias (200 nA) differential input; the scaling is 25 mV/dB, requiring a gain control voltage of only 1 V to span the central 40 dB of the gain range. An overrange and underrange of 1 dB is provided whatever the selected range. The gain control response time is less than 1 μs for a 40 dB change.

The differential gain control interface allows the use of either differential or single-ended positive or negative control voltages. Several of these amplifiers may be cascaded and their gain control gains offset to optimize the system SNR.

The AD603 can drive a load impedance as low as 100 Ω with low distortion. For a 500 Ω load in shunt with 5 pF, the total harmonic distortion for a ±1 V sinusoidal output at 10 MHz is typically −60 dBc. The peak specified output is ±2.5 V minimum into a 500 Ω load.

The AD603 uses a patented proprietary circuit topology—the X-AMP®. The X-AMP comprises a variable attenuator of 0 dB to −42.14 dB followed by a fixed-gain amplifier. Because of the attenuator, the amplifier never has to cope with large inputs and can use negative feedback to define its (fixed) gain and dynamic performance. The attenuator has an input resistance of 100 Ω, laser trimmed to ±3%, and comprises a 7-stage R-2R ladder network, resulting in an attenuation between tap points of 6.021 dB. A proprietary interpolation technique provides a continuous gain control function that is linear in dB.

The AD603 is specified for operation from −40°C to +85°C.

Applications

  • RF/IF AGC amplifiers
  • Video gain controls
  • A/D range extensions
  • Signal measurements

    • Data Sheet, Rev. H, 5/07

    Features

    • Linear-in-dB gain control
    • Pin-programmable gain ranges
      −11 dB to +31 dB with 90 MHz bandwidth
      9 dB to 51 dB with 9 MHz bandwidth
    • Any intermediate range, for example −1 dB to +41 dB with 30 MHz bandwidth
    • Bandwidth independent of variable gain
    • 1.3 nV/√Hz input noise spectral density
    • ±0.5 dB typical gain accuracy

    Diagrams

    AD603 Diagram
    Functional Block Diagram for AD603

    技术指标

    Supply Voltage (V) ±5V
    Gain Low End (dB) -11dB
    Gain High End (dB) +31dB
    -3 dB BW (MHz) 90MHz
    Spectral Noise (nV/rtHz) 1.4nV/rtHz
    Gain Accuracy (dB) ±0.5dB
    Supply Current (max) 20mA
    Package 8-Lead DIP,8-Lead SOIC

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    订阅新产品资料
    Part# Gain Control -3 dB BW (MHz) Gain Low End (dB) Gain High End (dB) Number of Channels Spectral Noise (nV/rtHz) Supply Voltage (V) Supply Current (max) Gain Accuracy (dB) 1 dB Comp Point (dBm) Package Price* (1000-4999)
    AD600 Analog 35 0 +40 2 1.4 ±5 14mA - - - $16.61
    AD602 Analog 35 -10 +30 2 1.4 ±5 14mA - - - $13.36
    AD603 Analog 90 -11 +31 1 1.4 ±5 20mA ±0.5 - 8-Lead DIP, 8-Lead SOIC $4.40
    AD604 Analog 40 0 +48 2 0.8 ±5 31mA ±0.3 15 24-Lead SOIC, 24-Lead SSOP $16.45
    AD605 Analog 40 -14 +34 2 1.8 +5 23mA ±0.2 15 16-Lead SOIC $9.91
    AD8260 Digital 180 -6 +24 1 2.4 +3.3 28mA +0.25 - - $3.84
    AD8320 Digital 150 -10 +26 1 53 +12 105mA ±0.2 22.5 20-Lead SOIC -
    AD8321 Digital 120 -27.4 +26 1 20 +9 90mA ±1 19.5 20-Lead SOIC $4.40
    AD8322 Digital 180 -12.6 +29.5 1 64 +5 113mA ±2 19 28-Lead TSSOP $3.19
    AD8323 Digital 100 -26 +27.5 1 - +5 - - - 28-Lead TSSOP $3.34
    AD8324 Digital 100 -25.5 +33.5 1 157 +3.3 207mA ±1 21 20-Lead LFCSP, 20-Lead QSOP $1.73
    AD8325 Digital 100 -29.5 +30 1 56 +5 133mA ±1 18.5