Anadigics, a leading supplier of wireless and broadband communications solutions, has announced a new multi-feature transimpedance amplifier (TIA). The second in a series of InGaP (indium gallium phosphide) HBT (heterojunction bipolar transistor) TIAs, the ATA7602 has been designed to deliver the high performance demanded by SONET OC-192 (10Gb/s) and DWDM fiber networks.

The ATA7602 is similar to its predecessor (ATA7601) in that it provides high bandwidth, low group delay, low noise performance, and low power consumption for high speed, broadband fiber optic systems. The new device delivers industry-leading group delay below 50ps, features extended optical overload performance up to 0dBm and provides a differential transimpedance of more than 2 kohm to achieve -19 dBm sensitivity. Most importantly, the -5.2VDC TIA offers a DC offset feature that enables external management of the duty cycle on both output pins.

"The ATA7602 is the second in a series of five planned products that leverages a common RF platform. This new product utilitizes our leading InGaP HBT process and was specifically designed with manufacturability in mind," noted Tom Lagatta, Vice President and General Manager of Fiber Communications Products at ANADIGICS. "This technique of "featurizing" a high performance RF engine gives us the ability to rapidly create a family of targeted OC-192 products, shortening time-to-market for our customers."

An improved product that offers a realistic solution to a problem is always welcome. Here, the previous ATA7601 InGaP OC-192 (10 Gbit/s) TIA has additional pads added that sniff the dc voltage on the differential output pair and with an outboard comparator loop can set up a variable dc offset at the input of the second stage; this gives the ability to maintain low duty cycle distortion with large signal operation or to allow the post amplifier to have a variable decision level.

Other changes are that the ATA7602 is specified as a -5.2 V VEE device, where the ATA7601 was specified as a +5.0 V VCC device. The supply current also increases to a typical 115 mA from a previous 65 mA, but the transimpedance has doubled while the sensitivity remains the same, and output return losses have improved.