Table I:

Trimodal SoC Measured Specifications

Optical Stimulation		Electrical Stimulation
VTG	2–4 V, 3 bits	Charge balance	Active+Passive
Freq.	2–50 Hz, 4 bits	Freq.	8–400 Hz, 4 bits
Pulse width	1.25–20 ms, 4 bits	Pulse width	40–640 μs, 4 bits
Current	0.8–24.8 mA, 5 bits	Current	±(25–775) μA, 5 bits
Light intensity	0–31.5 mW/mm2, 5 bits	Interphase delay	40–640 μs, 4 bits
ADC		Data Tx
Sampling rate	50 kS/s	Data carrier	RF 434 MHz, OOK
FoM	78.6 fJ	Packet loss rate	<0.13%
DNL	(−0.12–0.39) LSB	Tx-Rx distance	Up to 150 cm
INL	(−0.75–1.5) LSB	Date rate	6.78 Mbps
SNR	54.2 dB	Output power	−3–4 dBm, 3 bits
SFDR	64.1 dB	Data Rx
ENOB	8.7	Data carrier	Inductive link, 13.56 MHz, OOK
Neural Recording
LNA gain	40 dB	Data rate	50 kbps
VGA gain	15–30 dB, 3 bits	SoC
Low cut-off	1–100 Hz, 3 bits	Chip area	3×5 mm2
High cut-off	10 kHz	Average power consumption	20.7 mW
Input-referred noise	3.46 μVrms with in 1 Hz-50 kHz
		Supply volt.	1.8/3.3/4V
NEF	2.95	Voltage doubler eff.	82%
Recovery time	<0.4 ms