Amplifier for switching tube body bias and follower

Abstract

The invention discloses an amplifier for switching tube body bias and a follower. The amplifier comprises: a current source for providing a constant current; a current mirror connected to the current source, the current mirror having a first current branch and a second current branch coupled to each other; a non-inverting input end and a inverting input end which are respectively used for controlling the first current of the first current branch and the second current of the second current branch; and a limiting transistor which is located on the second current branch circuit, wherein the limiting transistor is of a first type, receives a fixed bias voltage and is used for limiting the second current, so that the output voltage is maintained to be smaller than or equal to the input voltage when the input voltage is close to zero voltage, or when the input voltage is close to the power supply voltage, the output voltage is maintained to be greater than or equal to the input voltage. The amplifier can obtain a transfer characteristic meeting a body bias condition.

Description

technical field [0001] The invention relates to the technical field of electronic devices, and more specifically, to an amplifier and a follower used for biasing a switching tube body. Background technique [0002] The body effect of the switch tube is the change of the threshold voltage (Vth) of the switch tube caused by the voltage difference between the source and the body region. The body effect can be suppressed by using body bias in the switch tube. For example, the body bias circuit is connected to the body region of the switch tube to provide a body bias voltage (body bias), thereby suppressing the influence of the potential of the body region on the threshold voltage of the switch tube, thereby reducing the value of the on-resistance and reducing the conduction voltage. On-resistance fluctuates with source voltage. The body bias voltage needs to be selected as an appropriate magnitude to avoid the leakage current caused by the conduction of the parasitic PN juncti...

AI Technical Summary

Problems solved by technology

However, since the transfer characteristics of the amplifier are not linear in the entire voltage range, when the input voltage is close to 0, the output voltage of the amplifier is greater than the input voltage, therefore, when the source terminal voltage of the switch tube is close to 0, the body bias circuit provides The body bias voltage of the switch is greater than the source voltage of the switch, which may still lead to the conduction of the parasitic PN junction

Images