| 摘要 |
PURPOSE: A current bias circuit of a cascode current mirror is provided to obtain the desired amount of current by connecting source terminals of NMOS transistors of a current bias circuit with a resistance and a negative feedback of an OP amplifier. CONSTITUTION: A cascode current mirror(10) is formed with a plurality of NMOS transistors(MP1 to MP5) having the structure of current mirror. Each source terminal of the NMOS transistors(MP1,MP3,MP5) outputs the same current value. A current bias circuit(30) is formed with an OP amplifier(40), an external resistance(R), and a band gap reference circuit(50). The OP amplifier(40) is commonly connected with each gate terminal of a couple of NMOS transistor(MN1,MN2). The external resistance(R) is connected with a common drain terminal of the NMOS transistor couple(MN1,MN2) and a negative terminal of the OP amplifier(40). The band gap reference circuit(50) receives voltage of a predetermined level and generates a constant reference voltage.
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