Low voltage class-AB output stages for CMOS Op-Amps

Three new class-AB output stages for CMOS op-amps with accurate quiescent current control using low-voltage techniques are proposed. These output stages make use of passive components (capacitors and resistors) and/or feedback to allow operation with a supply voltage close to a transistor threshold voltage. Three op-amps using the proposed output stages were sent for fabrication using a standard 0.8µm CMOS process and experimental results are provided showing a GBW = 15 MHz and rail-to-rail output swing using a voltage supply of 1.5V.