| 摘要 |
PURPOSE: A bias circuit of a CMOS amplifier is provided, which maintains a constant amplifier performance under a power supply voltage variation by increasing an output impedance by realizing a current mirror in a cascode structure. CONSTITUTION: A bias transistor part(200) supplies a bias voltage to transistors of an amplifier. A current mirror transistor part(210) is constituted with a current mirror to provide a current to the transistors of the bias transistor part. A cascode transistor part(240) increases an output impedance of the transistors in the current mirror transistor part. And an amplifier(230) comprises a number of transistors to supply the bias voltage of the cascode transistor part. Thus, the circuit maintains a constant amplifier performance under the power supply voltage variation by increasing the output impedance by constituting a bias circuit block for an analog/mixture mode circuit.
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