A Half-Shared Transimpedance Amplifier Architecture for High-throughput CMOS Bioelectronics

A common problem in single-cell measurement is the low-throughput nature of measurements. Monolithic CMOS microsystems have enabled many parallel measurements to take place simultaneously to increase throughput due to the integration of electrodes and amplifiers into a single chip. This paper explores a CMOS chip containing an array of 1024 parallel transimpedance amplifiers that takes advantage of a “half-shared” operational amplifier architecture. This architecture splits a traditional 5-transistor operational amplifier into two, the inverting half and the non-inverting half. Splitting an amplifier into two allows for the non-inverting half to be “shared” with several inverting halves, reducing the die area required for each individual amplifier. This allows for an increased number of amplifiers to be embedded into the same chip; in this case, 32 amplifiers are able to fit in the same space as 17 traditional 5-transistor operational amplifiers. The amplifiers exhibit low mismatch of 1.65 mV across the entire 1024 amplifier array, as well as high linearity in transimpedance gain. The technique will enable larger arrays to be created in future designs to allow electrophysiologists, among others, access to even higher-throughput measurement tools.