. Author manuscript; available in PMC: 2020 Aug 1.

Published in final edited form as: IEEE Trans Biomed Circuits Syst. 2019 May 23;13(4):608–618. doi: 10.1109/TBCAS.2019.2918761

Table II.

Measurement of FF-WIOS SoC Specifications

Overall system
ASIC area	1 mm²
Power with stimulation	1 mW (Average)
Power without stimulation	300 μW
Voltage doubler efficiency	43 %
Switch capacitor-based stimulation
Target voltage	5 V
Charging efficiency	37 %
Charging time	30 ms
C_s / C_LED / C_L	10 μF / 10 μF / 10 μF
Optical stim. efficiency	62.5 %
Stimulation parameters
Stimulation frequency	2.5 Hz ~ 10 Hz, 2 bits
Pulse width	0.5 ms ~ 2 ms, 2 bits
Current limiter	250 μA ~ 1 mA, 2.5 mA ~10 mA
Forward and back data telemetry
Data bits	12 bits
Pre/post-amble bits	10 bits
PPM data rate	50 kbps
LSK data rate	160 bps
BT pulse width	1 or 2 μs, 1 bit