QUALCOMM Incorporated
PMOS-OUTPUT LDO WITH FULL SPECTRUM PSR

Abstract:

A PMOS-output LDO with full spectrum PSR is disclosed. In one implementation, a LDO includes a pass transistor (M.sub.O) having a source coupled to an input voltage (Vin); a noise cancelling transistor (M.sub.D) having a source coupled to the Vin, a gate coupled to a drain and a gate of the pass transistor; a source follower transistor (M.sub.SF) having a source coupled to a drain of the pass transistor, a drain coupled to the drain and gate of the noise cancelling transistor; a current sink coupled between the drain of the source follower transistor and ground; and an error amplifier having an output to drive the gate of the source follower transistor.