Digitally Controlled VGA Features Wide Bandwidth

The AD8370 high-linearity, fully differential variable gain amplifier (VGA) is designed for use in wireless and wired communications networks. This digitally controlled part provides a 700-MHz bandwidth (−3 dB), enabling it to be used at intermediate frequencies (IF) up to 380 MHz. The AD8370 allows designers to choose between two gain control ranges—a high-gain mode adjustable from 6 to 34 dB and a low-gain mode adjustable from −11 to 7 dB. Selection is achieved through a 3-bit serial interface. This configuration gives designers the flexibility to fine-trim the gain with less than 1-dB resolution for maximum receiver sensitivity. Thanks to low intermodulation distortion, high output compression, low noise, and differential drive, the AD8370 makes an ideal pre-amplifier for high-speed, high-performance analog-to-digital converters (ADCs). This amplifier works with the company's line of ADCs, including the low 12-bit AD9226, AD9235, AD9433, and AD6640. This device is specified for use at a number of common IFs, including 70, 140, 190, 240, and 380 MHz. The AD8370 functions in automatic gain control (AGC) loops within cellular infrastructure equipment, such as GSM, CDMA, and W-CDMA. The AD8370 amplifier comes in a compact 16-pin TSSOP package. It operates over the range of −40°C to 85°C. The AD8370 is priced at $4.20 each in 1000-unit quantities.