| 摘要 |
PURPOSE:To make a low distortion at low voltage, etc., and to reduce frequency deviation by impressing the constant voltage from a bias circuit on the gate of the load MOSFET connected with the drain of the input differential MOSFET of a basic differential amplifier circuit, making the voltage into a constant current source and coupling an inversion output terminal with an input terminal. CONSTITUTION:In a differential amplifier step OTA, the load MOSFET M 1 and M 2 connected with the drain side of input differential MOSFET M 3 and M 4 are made into a constant current source, and a bias circuit BIAS generating the gate bias voltage is provided. The bias circuit BIAS is constituted to generate also the gate bias voltage of the MOSFET M 5 for constant current connected with the common source of input differential MOSFET M 1 and M 2. Because the amplitude of an input signal Vin for the operations of all the MOSFET in a saturation area is not requested to threshold Vthp from a formula, low voltage is used. Ve is the difference voltage of the inter-gate source voltage Vgs and threshold voltage Vthn of the FET M 3 and M 4, and VDD is power supply voltage.
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