Integrated circuit for emulating resistor

Abstract

An integrated circuit for emulating a resistor is based on the output resistance of a non-linear circuit element, such as a transistor. In the case of a transistor, it is biased into operation in its linear region, and a voltage dependent on the ac source-drain voltage is coupled to the gate voltage, thereby to improve linearity of the drain-source resistance with respect to the drain-source voltage. This modification to the gate voltage can be used to alter the transfer function such that the drain-source resistance is no longer dependent on the drain-source voltage.

Description

technical field [0001] The invention relates to integrated circuits for simulating resistors. Background technique [0002] Some applications require the use of resistors with good absolute resistance accuracy. The types of resistors available in semiconductor processes for making integrated circuits have limited absolute accuracy due to process variations. Resistor values ​​in a typical semiconductor process are generally considered to be parasitic effects that benefit analog design, and are usually not the main direction of optimization in the process. [0003] Therefore, the resistance variation of a resistor with a given geometry can be large and easily introduce + / - 10-30% uncertainty in absolute value. [0004] In cases where the accuracy of the absolute value of the resistor is important, such as in a characteristic line termination, it is necessary to have the ability to adjust the resistance to the desired value. One known method of resistance adjustment is to us...

AI Technical Summary

Problems solved by technology

However, the on-resistance of a MOS transistor with a fixed gate-source voltage Vgs varies with the drain-source voltage Vds, resulting in a non-linear current-voltage characteristic

Images