VCA821

宽带、大于 40dB 调节范围、dB 线性可变增益放大器

The device is a DC-coupled, wideband, linear in dB, continuously variable, voltage-controlled gain amplifier. It provides a differential input to single-ended conversion with a high-impedance gain control input used to vary the gain down 40 dB from the nominal maximum gain set by the gain resistor RG and feedback resistor RF.

The VCA821 device internal architecture consists of two input buffers and an output current feedback amplifier stage integrated with a multiplier core to provide a complete variable gain amplifier VGA system that does not require external buffering. The maximum gain is set externally with two resistors, providing flexibility in designs. The maximum gain is intended to be set between 6 dB and 32 dB. Operating from ±5-V supplies, the gain control voltage for the VCA821 device adjusts the gain linearly in dB as the control voltage varies from 0V to +2 V. For example, set at a maximum gain of 20 dB, the VCA821 device provides 20 dB, at VG = +2 V, to less than –20 dB at VG = 0 V. The VCA821 device offers excellent gain linearity. For a 20-dB maximum gain, and a gain-control input voltage varying between +1 V and +2 V, the gain does not deviate by more than ±0.3 dB maximum at +25°C.

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710-MHz Small-Signal Bandwidth

G = +2 V/V

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320 MHz, 4 VPP Bandwidth G = +10 V/V

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0.1-dB Gain Flatness to 135 MHz

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2500 V/µs Slew Rate

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> 40-dB Gain Adjust Range

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High Gain Accuracy: 20 dB ±0.3 dB

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High Output Current: ±90 mA