AD8330:  Low Cost DC to 150 MHz Variable Gain Amplifier

The AD83301 is a wideband variable gain amplifier for applications requiring a fully differential signal path, low noise, well-defined gain, and moderately low distortion, from dc to 150 ...More

AD8330:  Low Cost DC to 150 MHz Variable Gain Amplifier

Product Description

The AD83301 is a wideband variable gain amplifier for applications requiring a fully differential signal path, low noise, well-defined gain, and moderately low distortion, from dc to 150 MHz. The input pins can also be driven from a single-ended source. The peak differential input is ±2 V, allowing sine wave operation at 1 V rms with generous headroom. The output pins can drive single-sided loads essentially rail-to-rail. The differential output resistance is 150 Ω. The output swing is a linear function of the voltage applied to the VMAG pin that internally defaults to 0.5 V, providing a peak output of ±2 V. This can be raised to 10 V p-p, limited by the supply voltage.

The basic gain function is linear-in-dB, controlled by the voltage applied to Pin VDBS. The gain ranges from 0 dB to 50 dB for control voltages between 0 V and 1.5 V—a slope of 30 mV/dB. The gain linearity is typically within ±0.1 dB. By changing the logic level on Pin MODE, the gain decreases over the same range, with an opposite slope. A second gain control port is provided at the VMAG pin and allows the user to vary the numeric gain from a factor of 0.03 to 10. All the parameters of the AD8330 have low sensitivities to temperature and supply voltages.

Using VMAG, the basic 0 dB to 50 dB range can be reposi-tioned to any value from 20 dB higher (that is, 20 dB to 70 dB) to at least 30 dB lower (that is, –30 dB to +20 dB) to suit the application, thereby providing an unprecedented gain range of over 100 dB. A unique aspect of the AD8330 is that its bandwidth and pulse response are essentially constant for all gains, over both the basic 50 dB linear-in-dB range, but also when using the linear-in-magnitude function. The exceptional stability of the HF response over the gain range is of particular value in those VGA applications where it is essential to maintain accurate gain law-conformance at high frequencies.

An external capacitor at Pin OFST sets the high-pass corner of an offset reduction loop, whose frequency can be as low as 5 Hz. When this pin is grounded, the signal path becomes dc-coupled. When used to drive an ADC, an external common-mode control voltage at Pin CNTR can be driven to within 0.5 V of either ground or VS to accommodate a wide variety of requirements. By default, the two outputs are positioned at the midpoint of the supply, VS/2. Other features, such as two levels of power-down (fully off and a hibernate mode), further extend the practical value of this excep-tionally versatile VGA.

The AD8330 is available in 16-lead LFCSP and 16-lead QSOP packages and is specified for operation from −40°C to +85°C.

Applications

  • Pre-ADC signal conditioning
  • 75 Ω cable driving adjust
  • AGC amplifiers

    • 1 Protected by U.S. Patent No. 5,969,657; other patents pending.

    Features

    • Fully differential signal path and also used with single-sided signals
    • Inputs from 0.3 mV to 1 V rms, rail-to-rail outputs
    • Differential RIN = 1 kΩ; ROUT (each output) ,br>75 Ω
    • Automatic offset compensation (optional)
    • Linear-in-dB and linear-in-magnitude gain modes 0 dB to 50 dB, for 0 V < VDBS
      < 1.5 V (30 mV/dB)
    • Inverted gain mode: 50 dB to 0 dB at -30 mV/dB
    • x0.03 to x10 nominal gain for
      15 mV< VMAG < 5 V
    • Constant bandwidth: 150 MHz at all gains
    • Low noise: 5 nV/√Hz typical at maximum gain
    • Low distortion: ≤-62 dBc typ
    • Low power: 20 mA typ at VS of 2.7 V - 6 V
    • Available in space-saving 3 mm x 3 mm LFCSP package

    Diagrams

    AD8330 Diagram
    Functional Block Diagram for AD8330

    Specifications

    Supply Voltage (V) +6V
    Gain Low End (dB) 0
    Gain High End (dB) +50dB
    -3 dB BW (MHz) 150MHz
    Spectral Noise (nV/rtHz) 5nV/rtHz
    Gain Accuracy (dB) ±0.5dB
    Supply Current (max) 20mA
    Package 16-Lead LFCSP,16-Lead QSOP

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    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