Comparision of two different architectures of multichannel readout ASICs for neurobiological experiments

We present two different approaches to the multichannel recording ASICs dedicated for neurobiology experiments. The ASICs are processed in 180nm CMOS technology and occupy the same silicon area of 5×2.3 mm². Presented integrated circuits include 64 recording channels and have a possibility to tune their low and high cut-off frequencies. Each recording channel consumes about 200 μW of power and is characterized by the input referred noise as low as 6 μV rms. Both presented ASICs have good uniformity concerning the spread of their electrical parameters (like gain, corner frequencies, offsets, noise) from channel to channel. In order to decrease the number of output wires the 64:1 analog multiplexer is used in both cases. This paper presents the architecture, the layout, and the measurement results of the ASICs. Additionally it reports about the system we have built for neurobiology experiments that comprises of presented ASICs and micromachined recording electrodes. We show the preliminary measurements of action potentials from the thalamus of the rat under urethane anesthesia.