Obviating op amps
Overcoming the limitations of op amps in high gain, high speed feedback loops. By Paul Dempsey.
Like many aspects of analogue design, operational amplifiers (op amps) encounter numerous obstacles when scaled in cmos: specifically, signal swing and intrinsic device gain are reduced. Decreases in gain are a particular problem because, for a feedback based analogue signal processing system, this value determines output accuracy.
The Massachusetts Institute of Technology (MIT) unveiled its first step towards obviating the need for op amps in sampled data systems at the 2006 International Solid State Circuits Conference (ISSCC) and disclosed more progress at the same event in San Francisco this February. In the next few weeks, it hopes to announce a further breakthrough – scaling its prototypes from 180nm to 90nm.
