Grid drive circuit for metallic oxide semiconductor field effect transistor to output linear current

Abstract

A grid drive circuit for a metallic oxide semiconductor field effect transistor to output a linear current is provided. The grid drive circuit comprises a P-type metallic oxide semiconductor field effect transistor of diode connection configuration, an N-type metallic oxide semiconductor field effect transistor of diode connection configuration, and a voltage input circuit at least including a metallic oxide semiconductor field effect transistor. If an output voltage of the grid drive circuit is connected to a grid electrode of a metallic oxide semiconductor field effect transistor, the metallic oxide semiconductor field effect transistor outputs a current having a linear relationship with an input voltage. According to the invention, the circuit and the elements are simple, reducing production cost.

Description

technical field [0001] The invention relates to a gate drive circuit for making a metal oxide semiconductor field effect transistor output a linear current, in particular to a voltage-to-current conversion drive circuit for a metal oxide semiconductor field effect transistor with a simple structure. Background technique [0002] In digital circuits, the control terminal generally receives a voltage signal input, and some controls need to convert the input linear voltage into a linear current output, such as a voltage-controlled oscillator (VCO) in a phase-locked loop (PLL). It is converted into current in proportion; and when transmitting digital voltage signals over long distances, the resistance of the transmission line will attenuate the voltage signal, so the voltage signal must be converted into current before being transmitted in the form of current to reduce the influence of transmission line impedance on the signal. [0003] A known voltage-to-current converter is sh...

AI Technical Summary

Problems solved by technology

It combines the amplifier and the current mirror circuit to become an active current mirror differential pair, and the control voltage V in Input from the positive terminal of the amplifier, controlled by negative feedback, the virtual short circuit characteristic of the amplifier makes the resistance R s The upper terminal voltage is V -n , through resistor R s The amount of current is I out =V in / R s , current I out The output is converted by the current mirror; if the voltage source is 5V, when I out Level must be 10 -9 A, the resistor R s It takes 10 6 Ω level or above, polysilicon is used as the resistor in the chip, 10 6 In addition to requiring a large area to increase the cost of the Ω-level resistance value, the resistance value of polysilicon as a resistor can vary by up to ±25% due to process differences, which will affect the output accuracy.

There are also many voltage-current conversion methods that do not use resistors. Most of them use complex circuits to offset the nonlinear term in the MOSFET current formula, so that the output current calculation formula becomes a linear linear formula. In addition to the increase in cost, process differences will also affect the linearity of the circuit output. These are the areas where the voltage-current conversion circuit needs to be improved.

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