By Hank Russell

Texas Instruments ( Dallas, TX) has released a low-distortion 5V single-supply operational amplifier (op amp) designed for applications requiring high speed, low distortion and low noise. The THS4304 enables greater resolution and precision in wireless infrastructure, medical imaging and automated test equipment, and is suitable for high-speed signal conditioning applications such as driving high-resolution, high-speed analog-to-digital converters.

“We can do active filtering,” said Jim Karki, systems engineer and member of the Group Technical Staff at TI. “It’s a lot more flexible, too. Say you want a gain of 2.5 instead of a gain of 2. You can do that.”

According to the company, the THS4304 is the first unity gain stable op amp from TI’s BiCom-III complementary bipolar Silcion Germanium (SiGe) process. BiCom-III was developed for ultra-high precision analog integrated circuits by doping the base with germanium. “It’s a fully isolated process,” said Julio Acosta, TI’s design engineering manager. “The advantages of that will be lower capacitance and the silicon germanium will give us this speed.

Doping the base with germanium greatly increases carrier mobility and makes for extremely fast transient times. The process produces truly complementary bipolar NPN and PNP transistors with a transmit frequency of 18-19 GHz and a maximum frequency of 40-60 GHz. Complementary transistors enable the Class AB amplifier stages that are critical for the design of high-speed, high-performance analog circuits. “The beauty of the BiCom-III process is not in the speed itself,” Acosta explained. “Yes, it’s fast, but it makes the NPN and PNP transistors. It allows us to go to architectures like the one we have on the 4304, where we have a fully complementary architectures, which results in power savings.”