Patent ID: 6384685
Filing Date: 2002-05-07
Classification: H03F

Abstract:
A complementary metal oxide semiconductor (CMOS) class AB amplifier having an adaptive level shift circuit, a compensation capacitor and an output transistor pair to receive an output of a differential amplifying circuit for being provided with a DC bias and a DC amplifing effect by the adaptive level shift circuit, phase compensated by the compensation capacitor, and driven by the output transistor pair, the adaptive level shift circuit comprising:a current mirror circuit having a first NMOS transistor and a second NMOS transistor, each having a gate connected to one another; a NMOS diode transistor having a gate and a drain connected to the gate; a NMOS switch transistor having a source connected to a drain of the second NMOS transistor of the current mirror circuit, a drain connected to a drain of the first NMOS transistor of the current mirror circuit and a source of the NMOS diode transistor, and a gate connected to the gate and drain of the NMOS diode transistor; a PMOS input amplifier transistor having a drain connected to the drain of the NMOS diode transistor; and a PMOS current source transistor having a drain connected to the source of the NMOS switch transistor.