A Low-Power High-Immunity Capacitive-Isolation CMOS Information Transmission System

In this article, a low-power and high-immunity capacitive-isolation-based complementary metal-oxide–semicon- ductor (CMOS) information transmission system for ac-switch driving is proposed. As the implementation of an ac switch needs a floating ground (FG), the control signal of the ac switch should be applied via an electrical isolation system. Taking into account the design restrictions for our intended application: compatibility with CMOS technology, compatibility with magnetic resonance imaging (MRI) environment, low power, high immunity to FG, and short signal delay, only a capacitive-isolation system can be used. Moreover, unlike existing systems, a second-order high-pass filter is deployed allowing not only considerable power reduction but also floating-ground immunity increase. The proposed system was designed in AMS CMOS HV 0.35-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m technology. The simulation results show a tolerance of FG up to 240 Vpp at 1 MHz, which gives an FG immunity up to 720 V/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>s. Moreover, with the choice of 100 MHz as the carrier signal, the signal transmission delay is no more than 11 ns, nearly 1% of the signal cycle, and the power consumption down to 1.38 mW, nearly 50% drop compared to the existing design. Both process, voltage, and temperature (PVT) simulations and preliminary experimental results are also given.