| 摘要 |
A low noise differential amplifier includes a differential stage and first and second unbalanced differential feedback amplifiers. The differential stage includes first (13) and second (14) load devices coupled to first (11) and second (12) conductors, respectively, a resistor (RS), a first input transistor (Q1) having a first electrode coupled to the first conductor and a second electrode coupled by a third conductor (16) to a first terminal of the resistor (RS), and a second input transistor (Q2) having a first electrode coupled to the second conductor (12) and a second electrode coupled by a fourth conductor (17) to a second terminal of the resistor (RS). The first feedback amplifier (18) includes a third input transistor (Q5) coupled between the third conductor (16) and the first current source transistor (Q3). The first feedback amplifier (18) drives the control electrode of the first input transistor (Q1). The second feedback amplifier (19) receives an input signal (VIN-), and drives to control electrode of the second input transistor (Q2), the second feedback amplifier (19) producing a second signal (25) on the control electrode of the second input transistor (Q2). A first current source produces a first bias current through the first load device (13), the first input transistor (Q1), and the third input transistor (Q5). A second current source produces a second bias current flowing through the second load device (14), the second input transistor (Q2), and the second feedback amplifier.
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