An implantable 700μW 64-channel neuromodulation IC for simultaneous recording and stimulation with rapid artifact recovery

Abstract

We present an 180nm HV CMOS IC for concurrent neural stimulation and recording that combines 64 low-noise recording front-ends and 4 independent stimulators multiplexed to any of the 64 channels. The stimulators have 5mA peak current, 12V compliance and dynamic power management to maximize efficiency. Co-design of the stimulation and recording subsystems resulted in 100mV of recording linear range, 70nV/rtHz noise, and a rapid 1ms (single-sample) artifact recovery during stimulation.

A wireless and artefact-free 128-channel neuromodulation device for closed-loop stimulation and recording in non-human primates

“…Integrated circuits are required to minimize area and power for a large number of recording and stimulation channels. We customdesigned a neuromodulation integrated circuit (NMIC) to deliver stimulation pulses ranging from subthreshold currents (down to 20 µ A) to those required by DBS (5 mA), and to record local field potentials (LFPs) with a bandwidth of up to 500 Hz 26 . We chose LFPs as the signals of interest for their usefulness in medical applications as an indicator of disease 8,[27][28][29][30] .…”

“…Saturation can be prevented by increasing the amplifier linear input range and tolerance to d.c. current offset 21,26,46 , or by subtracting the large amplitude components of the artefact 47,48 . Artefact duration can be reduced by rapidly clearing charge built up on circuit elements from stimulation 25,26,49,50 . We have designed the NMICs with improved stimulation and recording architectures to both prevent large indirect artefacts and minimize their effects on the front-end circuits.…”

Sub-<inline-formula> <tex-math notation="LaTeX">$\mu$ </tex-math> </inline-formula>Vrms-Noise Sub-<inline-formula> <tex-math notation="LaTeX">$\mu$ </tex-math> </inline-formula>W/Channel ADC-Direct Neural Recording With 200-mV/ms Transient Recovery Through Predictive Digital Autoranging

“…As such, the rapid transient recovery capability of PDA tracking large-slope artifacts comes at a temporary partial loss in signal resolution, which reestablishes its noise-limited level upon completion of the transient. Since typical neural signals are low amplitude and have a 1/ f 2 low-pass power spectrum profile [8], PDA according to (10) maintains near-optimal resolution in the absence of artifact transients. Side-by-side comparison of the BioADC with a commercially available neural data acquisition system (Intan RHD-2132 [19], using the default fast-settling feature).…”

“…Full-duplex neural interfaces for closed-loop neural modulation require simultaneous operation of electrical recording and stimulation. Stimulation artifacts produce rapid and large-amplitude transients in the recorded signals that easily overwhelm the neural response signals, necessitating a paradigm shift in the design of neural recording toward very high input dynamic range and fast transient response [10].…”

“…Hybrid architectures utilizing oversampling ADCs with digital feedback to the AFE [8], [10] have seen recent adoption due to their increased power and area efficiency. Recent integrated designs combining AFE and ADC in one stage [9] offer further improvements in integration density and expanded input dynamic range.…”