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Current source with very high output impedance

A technology of output impedance and current source, applied in the field of current source, can solve problems such as insufficient output impedance, high power supply voltage, large voltage margin, etc., achieve low power consumption, increase output impedance, and occupy a small chip area.

Inactive Publication Date: 2005-11-30
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But this will consume a large voltage margin, and at the same time, require a higher power supply voltage
[0004] There are some problems in the actual current source circuit, such as the output impedance is not large enough, the stable output current needs to be realized at a higher voltage, etc.

Method used

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  • Current source with very high output impedance
  • Current source with very high output impedance
  • Current source with very high output impedance

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Embodiment Construction

[0048] A current source with extremely high output impedance proposed by the present invention, its structural block diagram is as follows figure 2 Shown, including a current source generating circuit and an equivalent negative resistance generating circuit. The current source generating circuit is used to generate a positive resistance and a reference current. This current source generating circuit can be implemented with all current source circuits. Here we only use the cascode current mirror circuit as an implementation to illustrate the working principle:

[0049] The current source generation circuit is implemented with a Cascode current mirror, including:

[0050] (1) A current reference source Iref1 is used to generate a constant current, one end of which is connected to an external power supply, and the other end is connected to the drain of the NMOS transistor M3.

[0051] (2) Four NMOS transistors (M1, M2, M3 and M4) are used to generate the mirror current of Ire...

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Abstract

A current source provided with high output impedance comprises a current source-generating circuit and a equivalent negative resistance generating circuit, wherein, the said current source-generating circuit can comprise all the current source circuit such as Cascode, Wilson, or Widlar current mirror and so on to generate positive resistance and reference current; the said negative resistance generating circuit comprises a short-circuit grid-drip POMS pipe, a NMOS pipe and an amplifier to generate equivalent negative resistance whose absolute value is made larger than the former one through designing; then the said equivalent negative resistance is connected in parallel with the said positive resistance to get super high output resistance whose value is close to 109 ohm magnitude order.

Description

technical field [0001] The invention belongs to the field of electronic technology, and in particular relates to the current source technology in the field of integrated circuits. Background technique [0002] A current source is a circuit whose output current remains constant as its terminal voltage changes. It is an important part of an analog integrated circuit and has a wide range of demands in an analog integrated circuit. For current, there are no losses on long metal wires, but for voltage, current sources are preferred in complex analog circuits with long metal wires. "Analysis and Design of Analog Integrated Circuits" (4 th Edition) presents various types of current sources, which, as described in the book, can be used both as biasing elements and as active loads for amplifier stages. Among them, the output impedance of the current source is an important parameter of the current source circuit, and the higher the output impedance, the more stable the output curre...

Claims

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Application Information

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IPC IPC(8): G05F3/26
Inventor 罗萍余磊李肇基张波
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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