1 MHz to 1.2 GHz VGA with 30 dB Gain Control Range
The ADL5331 is a high performance, voltage-controlled variable gain amplifier/attenuator for use in applications with frequencies up to 1.2 GHz. The balanced structure of the signal path maximizes signal swing, eliminates common-mode noise and minimizes distortion while it also reduces the risk of spurious feed-forward at low gains and high frequencies caused by parasitic coupling.
The 50 Ω differential input system converts the applied differential voltage at INHI and INLO to a pair of differential currents with high linearity and good common-mode rejection. The signal currents are then applied to a proprietary voltage controlled attenuator providing precise definition of the overall gain under the control of the linear-in-dB interface. The GAIN pin accepts a voltage from 0 V at a minimum gain to 1.4 V at a full gain with a 40 mV/dB scaling factor over most of the range.
The output of the high accuracy wideband attenuator is applied to a differential transimpedance output stage. The output stage provides a differential output at OPHI and OPLO, which must be pulled up to the supply with RF chokes or a center-tapped balun.
The ADL5331 consumes 240 mA of current including the output pins and operates off a single supply ranging from 4.75 V to 5.25 V. A power-down function is provided by applying a logic low input on the ENBL pin. The current consumption in power-down mode is 250 μA.
The ADL5331 is fabricated on an Analog Devices, Inc., proprietary high performance, complementary bipolar IC process. The ADL5331 is available in a 24-lead (4 mm × 4 mm), Pb-free LFCSP_VQ package and is specified for operation from ambient temperatures of −40°C to +85°C. An evaluation board is also available.
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This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
ADL5331-EVALZ is a fully populated, 4-layer, FR4-based evaluation board designed to allow easy evaluation of all features of the ADL5331 analog controlled VGA. The evaluation board contains bypassable transformers to allow single ended or differential inputs and outputs. A pin on an eight pin right angle header connector is used to access the analog gain control pin. This evaluation board requires only a single supply within the range of 4.5 V to 5.5 V.