Chopper Capacitively Coupled Instrumentation Amplifier Capable of Handling Large Electrode Offset for Biopotential Recordings

This brief presents the design of a low-noise chopper capacitively coupled instrumentation amplifier (CCIA). To accommodate the input with large electrode offset (EOS), the amplifier includes a coarse digital dc-servo loop (DSL) in addition to a fine analog DSL that strikes a balance among noise, EOS handling range and circuit complexity. The chip is fabricated in a standard 0.13-<inline-formula> <tex-math notation="LaTeX">$ {\mu }\text{m}$ </tex-math></inline-formula> CMOS process. The supply voltage is 1.2 V and the quiescent current is 2.9 <inline-formula> <tex-math notation="LaTeX">$ {\mu }\text{A}$ </tex-math></inline-formula>. Measurement result shows that the chopper CCIA achieves a noise spectrum of 47 nV/<inline-formula> <tex-math notation="LaTeX">$\sqrt {{\text {H}}z}$ </tex-math></inline-formula> and is capable of handling EOS of ±50 mV.

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