Analog Devices Introduces High-Performance RF/IF Variable-Gain Amplifier

Analog Devices AD8368

Optimized to deliver the highest performance for wireless infrastructure applications, ADI's AD8368 VGA provides high linearity over a wide frequency range and integrates an on-chip rms detector.

Analog Devices, Inc. extended its portfolio of radio frequency (RF) integrated circuits (ICs) with a new analog-control variable-gain amplifier (VGA) that offers exceptional linearity over a broad frequency range for wireless infrastructure applications, such as cellular base station radio transceivers. The AD8368 is optimized to maintain dynamic range of base station radio transceivers, ensuring that both weak and strong incoming call signals are effectively handled and maintained. In addition, the AD8368 simplifies and reduces the number of external components required by integrating an accurate root-mean-square (rms) power detector on chip, which enables a complete automatic gain control (AGC) loop within a small 4 mm × 4 mm IC package.


The AD8368 is capable of sustaining high linearity (OIP3 of 34 dBm at 70 MHz) at the highest intermediate frequencies (IFs), allowing it to be used in all wireless standards, including 2G and 3G, as well as emerging broadband wireless standards such as 802.16 (WiMAX). The 380-MHz frequency range of the AD8368 allows the device to be used in both receive and transmit paths within any wireless infrastructure standard where the use of one or more AGC loops optimizes the base station dynamic range or allows the designer to add additional gain for optimal signal dynamic range and sensitivity.

The excellent linear-in-dB gain control conformance and flatness of the AD8368 can be attributed to ADI’s X-AMP® architecture, an innovative technique for implementing high-performance, continuous variable gain control. The AD8368 provides continuous 34-dB linear-in-dB gain control from –12 dB to + 22 dB. With a 3-dB bandwidth of 800 MHz independent of gain setting, a single-ended input and output drive, and exceptional linearity over the full operating range, the AD8368 is ideally suited for use in GSM, CDMA2000, W-CDMA, and TD SCDMA cellular base stations. Operating from a single supply voltage of 4.5 V to 5.5 V, the AD8368 consumes only 54 mA of current.

Availability and Pricing
The AD8368 is sampling now with full production scheduled for April 2006. The device is priced at $4.55 per unit in 1,000-piece quantities, is available in a 24-pin LFCSP (lead frame chip scale package), and is specified over an operating temperature range of – 40°C to + 85°C.

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