Table 1.

Current source Comparison.

References	Output impedance	Manufacturing process	Voltage and max current range
2007 KHU Mark1 [73]	1 MΩ @500 kHz	Separated component	N/A
2010 KHU Mark2 [71,91]	greater than 1 MΩ@1 MHz	Separated component	N/A
2014 KHU Mark2.5 [92]	at least 1 MΩ in the entire frequency range	Separated component	N/A
2009 Hong et al. [93]	160 kΩ@1 MHz	0.35 μm CMOS	±2.5 V 1 mA
2014 Constantinou et al. [88]	665 kΩ@ 100 kHz 372 kΩ @ 500 kHz 64 kΩ @1 MHz	1.6 μm CMOS HV	±9 V 5 mA
2017 Wu et al. [94]	750 kΩ @500 kHz	0.18-μm CMOS	±1.65 V 1 mA
2017 Jang et al. [95]	1 MΩ @1 MHz	65 nm CMOS	1.2 V 400uA
2018 Rao et al. [26,27]	100 kΩ @1 MHz	0.18-μm CMOS	3.3 V 1 mA