| 摘要 |
PURPOSE:To obtain a GaAs broad band amplifier excellent in the distortion characteristic by connecting two series of single amplifier stages of negative feedback coupling GaAsFET internally and leading out respectively an external terminal from a gate of the GaAsFET of the 1st stage, a drain of GaAsFETs of each stage and a common source of GaAsFETs of each stage. CONSTITUTION:Two series of 2-stage coupling amplifiers comprising GaAsFETs T1A, T1B, T2A, T2B are arranged, the sources are used in common on one chip. Further, the phase inverting circuit is constituted in a form of balun and mounted externally to input terminals 1, 3 of each series. The GaAsFETs T1A, T1B, T2A, T2B are constituted respectively to have, e.g. gate width of 1,000mum, and gate length of 1mum and gm of 100ms. The gate bias is applied from a terminal 2 and the drain bias is applied by mounting externally a choke coil to terminals 4, 5, 7, 8. The negative feedback amount of each stage depends on feedback resistors R3A, R3B, R4A, R4B. Thus, a broad band amplifier where only the distortion is improved without decreasing the NF gain is attained.
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