Patent ID: 7224209

Claim:
A speed up circuit for initiation of PTAT (proportional to absolute temperature) biasing circuit comprising: a MOS transistor of a first conductivity type with a source connected to a first power supply voltage source, a gate connected to receive a power indication signal, and a drain; a first MOS transistor of a second conductivity type with a drain connected to receive a PTAT biasing voltage from said PTAT biasing circuit, a gate in communication with said drain of said MOS transistor of the first conductivity type, and a source connected a second power supply voltage source; and a second MOS transistor of the second conductivity type with a drain in communication with the drain of the MOS transistor of the first conductivity type and the gate of the first MOS transistor of the second conductivity type, a gate connected to receive a feedback signal from said PTAT biasing circuit, and a source connected to the second power supply voltage source; wherein when said power indication signal denotes that said first power supply voltage source has not achieved a threshold level during activation of said first power supply voltage source, said drain of said MOS transistor of the first conductivity type is at a first voltage level to activate said first MOS transistor of the second conductivity to force said PTAT biasing voltage to a voltage level of said second power supply voltage source; and wherein when said feedback signal indicates that said PTAT biasing circuit has achieved a normal biasing voltage level, said second MOS transistor of the second conductivity type is activated and said first MOS transistor of the second conductivity type is deactivated and said PTAT biasing voltage is set to an active biasing level.