Bias current generation systems are disclosed. In one embodiment, a bias current generation system comprises a proportional to absolute temperature (PTAT) current source generating a PTAT current, a constant current source generating a constant current, a first current mirror forwarding the PTAT current, a second current mirror forwarding an adjusted current, where the adjusted current is the constant current subtracted by the PTAT current if the constant current subtracted by the PTAT current is greater than zero or the adjusted current is zero if the constant current subtracted by the PTAT current is less than zero, a third current mirror forwarding the adjusted current and a fourth current mirror forwarding a bias current generated by subtracting the PTAT current from the adjusted current.