Patent ID: 7605655
Filing Date: 2009-10-20
Classification: H03F

Abstract:
1. A highly linear differential amplifying circuit, comprising: a differential amplifying unit including a main differential amplifying unit having a differential pair of transistors for amplifying a difference of two input signals and an auxiliary amplifying unit connected in parallel with the main differential amplifying unit, wherein the second-order derivatives of transconductances of the main differential amplifying unit and the auxiliary differential amplifying unit are properly set to have some offset; and a source degeneration resistor unit including a first source degeneration resistor connected between an external first inductance element and a source of a first main transistor included in the main differential amplifying unit, a second source degeneration resistor connected between an external second inductance element and a source of a second main transistor included in the main differential amplifying unit, a third source degeneration resistor connected between a common connection terminal of sources of the first and second auxiliary transistors included in the auxiliary differential amplifying unit and the first source degeneration resistor, and a fourth source degeneration resistor connected between the common connection terminal of the sources of the first and second auxiliary transistors and the second source degeneration resistor.