Reference current source circuit and system

[0014]Referring to FIGS. 2 and 3 of the drawings, a reference current source circuit and its system according to a preferred embodiment of the present invention are illustrated, comprising a reference voltage generating module VREF, a voltage buffer connected to the reference voltage generating module VREF, an equivalent resistor connected to the voltage buffer, a filter capacitor C1 connected to the voltage buffer, a current mirror module connected to the voltage buffer and a reference current outputting terminal lout connected to the current mirror module, wherein the voltage buffer comprises an operational amplifier OP and a first FET M1 connected to the operational amplifier OP; the current mirror module comprises a second FET M2 and a third FET M3 connected to the second FET M2; the equivalent resistor comprises an oscillator OSC, a fourth FET M4 connected to the oscillator OSC, a fifth FET M5 connected to the oscillator OSC and a capacitor C2 connected to the fourth FET M4 and th