Chopper Modulation Improves OTA Information Transmission

We have investigated information transmission in operational transconductance amplifiers (OTA) using chopper modulation. Previous work showed that the optimal frequency bandwidth for an OTA was much higher than typical operating frequencies. Here we analyze the information transfer rates for a folded cascode amplifier and a chopper modulated folded cascode amplifier using the principles of information theory. The frequency transfer characteristic and intrinsic physical noise source of each device is modeled using process dependent noise parameters and the waterfilling technique is applied to determine the capacity as well as information rates for low frequency signals. Simulations are experimentally verified using circuits fabricated in a commercially available 3-metal, 2-poly 0.5 μm CMOS process.