Sink current and source current generating circuit

Abstract

The invention relates to a sink current and source current generating circuit, which comprises a voltage-current conversion circuit, a stable bias current generating circuit, a source current output circuit and a sink current output circuit. The voltage-current conversion circuit is used for converting reference voltage Vref into current I1 to produce first bias voltage Vb1; the stable bias current generating circuit is used for obtaining high-stability bias current to produce second bias voltage Vb2; the source current output circuit is an output branch used for producing PMOS (P-channel metal oxide semiconductor) source current based on the principle of a PMOS tube current mirror; and the sink current output circuit is an output branch used for producing NMOS (N-channel metal oxide semiconductor) sink current based on the principle of an NMOS tube current mirror. The reference voltage Vref in the system can be directly adopted, the characteristics of high precision and low temperature drift of Vref can be utilized, the bias current of the same high precision and low temperature drift can be obtained, and the problems of high requirements for the precision and temperature coefficient of the bias current in certain circuits can be solved.

Description

technical field [0001] The invention relates to a bias current source, in particular to a generating circuit for sinking and pulling current, which is a bias current source with a low temperature coefficient, and can obtain an output current value with a small temperature coefficient during operation. Background technique [0002] In various integrated circuit systems on a chip, such as power management chips, digital-to-analog / analog-to-digital converters, etc., the bias current source provides appropriate bias for each analog module of the system and becomes an indispensable part of the system. Based on the requirements of on-chip applications, the reference current source should not change with changes in temperature, voltage and various process parameters. Since the current large-scale circuits generally use CMOS technology, in order to realize system integration, the current source based on CMOS technology has become a core module of the whole circuit. Most of the ex...

AI Technical Summary

Problems solved by technology

Most of the existing bias circuits adopt self-bias circuit structure, such as figure 1 as shown, figure 1 (a) is a reference voltage source circuit, which directly obtains the output bias current (M6 branch) from the self-bias part of the reference voltage source. This method is relatively simple and easy, but the accuracy is not high, and because M6 copies the M5 branch The current of the circuit obviously has a positive temperature coefficient, and the output bias current will change with the temperature of the application environment; figure 1 (b) is a self-bias circuit, which can provide a relatively stable current, but due to the threshold voltage, mobility and resistance of CMOS devices have a certain temperature coefficient, so the bias current also has a certain temperature coefficient

For some circuits that require high current accuracy and temperature characteristics, the traditional bias circuit cannot meet the requirements

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