Voltage follower of small output resistance, large output amplitude

Abstract

Characters of the voltage follower are that a feedback loop is composed of one PMOS input tube M1, first current source I2, two NMOS tubes M2 and M3, a current sink I1, and second current source I3. The feedback loop reduces output resistance, and increases output amplitude of the voltage follower remarkably. At same time, drain electrode of the input tube of the voltage follower becomes a node with low impedance so as to make fluctuation of drain voltage of the input tube become smaller as well as reduce effect of channel modulation of input tube. Advantages are: small output resistance, large output amplitude, high linearity, and suitable to be operated at low voltage.

Description

technical field [0001] The invention belongs to the design of ultra-large-scale integrated circuits in the field of microelectronics and solid-state electronics, and relates to a new type of voltage follower circuit, which can be widely used in source attenuation structure transconductance amplifiers and tube-based transconductance amplifiers operating in the linear region, etc. circuit design. Background technique [0002] As the feature size of the CMOS process begins to enter the nanometer level, analog circuits need to work at lower and lower power supply voltages to meet the requirements of the process. But the threshold voltage of the transistor (V T ) and saturation voltage (V Dsat ) does not decrease linearly with the supply voltage synchronously. These factors severely limit the voltage amplitude of analog circuits at low supply voltages. In the published literature, a variety of methods have been proposed to allow analog circuits to operate at low voltages whil...

AI Technical Summary

Problems solved by technology

[0012] In addition, in some applications such as source-level attenuating transconductance amplifiers, the voltage follower needs to have a very small output resistance to achieve good linearity. The output resistance of the above two voltage followers cannot meet this requirement well.

In addition, because the drain of the above-mentioned voltage follower is very high impedance, it will bring a large voltage fluctuation at this point, so the channel modulation effect of the output transistor will be more obvious

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