The AD8375 and AD8376 from Analog Devices are high performance, fine-gain-step, digitally-controlled variable-gain amplifiers (VGAs) ideally suited for automatic gain control (AGC) within next-generation digital receivers for 2.5G, 3G, 4G, and WiMAX base stations. With the trend toward reducing size and increasing signal bandwidths within next-generation, multi-carrier base station designs, the AD8375 and AD8376 VGAs reduce component cost, board area, and power consumption—all while delivering unparalleled performance.
The AD8375 is a single-channel device, and the AD8376 is the industry’s first dual VGA. Both devices provide a highly integrated solution to replace discrete circuits comprising digital attenuators and intermediate frequency (IF) amplifiers required on a per channel basis within the IF signal path. Their 1-dB fine-gain-control steps and ±0.2-dB step accuracy allow designers to replace discrete implementations, representing an industry first for an integrated digitally-controlled VGA. The gain is controlled by a 5-bit digital interface over –4-dB to 20-dB range. The dual AD8376 provides two independent 5-bit digital interfaces and is ideally suited for use in main and diversity receiver designs.
Both the AD8375 and AD8376 provide unequalled linearity, with an output third-order intercept (OIP3) of 50 dBm at 140 MHz on just 130 mA current per channel. The high linearity minimizes distortion and eases design, allowing designers to maximize the signal level prior to the analog-to-digital converters (ADCs) across a broad choice of IFs up to 400 MHz. The AD8375 and AD8376 are for use with the most advanced high-performance ADCs such as ADI’s AD9640 / AD9445 and the recently announced AD6655 diversity IF receiver.
The AD8375 and AD8376 simplify the IF signal path for next-generation base station receivers supporting the trend to multi-carrier wideband radio designs for W-CDMA, S3G/LTE, CDMA2000, TDS-SCDMA, GSM EDGE Evolution, and broadband WiMAX standards. The AD8375 and AD8376 support new multi-carrier radio receivers with higher data throughput and capacity enhancements, and are ideal for smaller, higher capacity 3G and 4G base stations.
Availability and Pricing
Fabricated on Analog Devices’ proprietary XF3 silicon on insulator (SOI) SiGe complementary bipolar process, the AD8375 and AD8376 are sampling now and will be available in full production quantities in June 2007. The single-channel AD8375 is priced at $4.49 per unit, and the dual AD8376 is priced at $6.49 per unit in 1,000-piece quantities. Both devices are packaged in small footprint LFCSP (lead-frame chip-scale packages); 24-lead for the AD8375 and 32-lead for the AD8376.