Description
AD8367 AGC Linear dB Continuous Analog Automatic Gain Control Variable Gain Optical Amplifier Wide Bandwidth Detector
Product Description
A large number of filter capacitors are used for power decoupling, and a large area of ground and perforated holes are all designed in accordance with high-frequency circuits and have good frequency characteristics.
Specification
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item
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value
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Name
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AD8367 AGC voltage gain module
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Size
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50mm X 50mm
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Supply voltage range
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+5V
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Installation Instructions
Chip description
The AD8367 is a high performance 45 dB variable gain amplifier with linear-in-dB gain control for use from low frequencies up to several hundred megahertz. The range, flatness, and accuracy of the gain response are achieved using Analog Devices’ X-AMP® architecture, the most recent in a series of powerful proprietary concepts for variable gain applications, which far surpasses what can be achieved using competing techniques.
The input is applied to a 9-stage, 200 Ω resistive ladder network. Each stage has 5 dB of loss, giving a total attenuation of 45 dB. At maximum gain, the first tap is selected; at progressively lower gains, the tap moves smoothly and continuously toward higher attenuation values. The attenuator is followed by a 42.5 dB fixed gain feedback amplifier—essentially an operational amplifier with a gain bandwidth product of 100 GHz—and is very linear, even at high frequencies. The output third order intercept is +20 dBV at 100 MHz (+27 dBm, re 200 Ω), measured at an output level of 1 V p-p with VS = 5 V.
The analog gain-control input is scaled at 20 mV/dB and runs from 50 mV to 950 mV. This corresponds to a gain of −2.5 dB to +42.5 dB, respectively, when the gain up mode is selected and +42.5 dB to −2.5 dB, respectively, when gain down mode is selected. The gain down, or inverse, mode must be selected when operating in AGC in which an integrated square-law detector with an internal setpoint is used to level the output to 354 mV rms, regardless of the crest factor of the output signal. A single external capacitor sets up the loop averaging time.
The AD8367 can be powered on or off by a voltage applied to the ENBL pin. When this voltage is at a logic LO, the total power dissipation drops to the milliwatt range. For a logic HI, the chip powers up rapidly to its normal quiescent current of 26 mA at 25°C. The AD8367 is available in a 14-lead TSSOP package for the industrial temperature range of −40°C to +85°C.
Chip feature
1. Wide bandwidth (-3 dB bandwidth): 500 MHz 2. Linear dB continuous analog gain control 3. On-chip integrated square law detector for AGC operation 4. High linearity output IP3: 36.5 dBm (70 MHz) 5. High output compression P1dB: 8.5 dBm (70 MHz) 6. Single-ended 200Ω input impedance 7. Gain control range: 45 dB (maximum gain 42.5 dB)
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