Information capacity and power efficiency in operational transconductance amplifiers

Noise limits information transmission in analog systems. Real analog systems possess intrinsic physical noise such as thermal noise and flicker noise and inevitably suffer degradation of information content. This loss in information can be reduced if the analog system operates at frequencies where noise is minimal. Using principles of low power circuit design and information theory, we present a method to estimate the information transfer rates of analog systems and to determine the maximum theoretical limit. We have applied our method to an operational transconductance amplifier (OTA) and show that measured data corroborates our analytical predictions. We find a significant increase in information content if the system is operated in spectral regions with lower noise.