| 摘要 |
PURPOSE: High frequency variable amplifier circuits are provided which makes linear the existing gain that changes into logs and simplifies the circuit with the moss transistor. CONSTITUTION: The high frequency variable amplifier circuits comprise the gain control part (10) which gets the gain control voltage and the bias voltage and outputs the linear output signal using the threshold voltage of the moss transistor (NM1, NM2, NM3), the level shifter (20) which gets the permission of the output and shifts the static pressure level to the proper bias voltage, and the linear amplification part which amplifies the input voltage as much as the gain controlled by the level shifter output. This simple circuit changes the linear amplification part from the log scale to the linear scale.
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