Differential reference voltage buffer

Abstract

The invention provides a differential reference voltage buffer. The differential reference voltage buffer comprises a buffer stage, a control circuit, a current compensation circuit and a driving stage, wherein the buffer stage comprises at least a first transistor and a second transistor; the control circuit is connected with the buffer stage and forms a negative feedback structure used for generating a differential reference voltage; the current compensation circuit is used for compensating for a resistive load current of the control circuit; the driving stage is used for generating and outputting the differential reference voltage. The differential reference voltage buffer has the advantages that an external input reference voltage and a common mode input voltage generate the differential reference voltage, wherein a common mode voltage can be separately set, and the flexibility is high; the current compensation circuit compensates for a current generated in a resistance network inthe control circuit, so that the current in following devices in the buffer stage is not affected by the control circuit, and the differential reference voltage with high precision output can be generated; the driving stage works in an open-loop state and has faster response speed, so that the differential reference voltage buffer has high precision, fast response and common mode voltage capable of being set independently, thereby breaking through the limitations of application.

Description

technical field [0001] The invention relates to the field of integrated circuits, in particular to a differential reference voltage buffer. Background technique [0002] Precise and stable differential voltage references are required in many integrated circuits and circuit units, such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), linear regulators, and switching regulators. An ideal reference voltage source is not affected by power supply and temperature, and can provide a stable voltage in the circuit. In an analog-to-digital converter ADC, such as a pipelined or successive-approximation analog-to-digital converter structure, since the sampling capacitance is usually large, a differential reference voltage buffer is required to perform a reference voltage from a bandgap reference circuit. The differential conversion and buffer output can provide a large output current when needed, so that the circuit can complete the signal establishment quic...

AI Technical Summary

Problems solved by technology

[0003] At present, the traditional differential reference voltage buffer circuit structure usually includes three parts: a differential voltage source generation circuit, a buffer stage and a driver stage. Voltage V refp and V refn ; then the buffer stage to the differential reference voltage V refp and V refn Perform source follower output; the final drive stage provides low impedance and large current, and outputs a differential reference voltage V REFOUTP and V REFOUTN , which are respectively equal to the differential reference voltage V refp and V refn , in the differential reference voltage buffer circuit, the structure of the buffer stage combined with the driving stage is generally adopted due to its advantages of fast speed and low power consumption, but the existing differential reference voltage buffer also has obvious disadvantages: on the one hand, If in order to ensure the high precision and response speed of the voltage buffer, the common-mode voltage of the differential reference voltage cannot be set independently, which greatly limits the application of the buffer; on the other hand, if the common-mode voltage of the differential reference voltage The mode voltage can be set separately, and it will cause its resistance feedback network to generate current and flow into the buffer stage, causing the current ratio of the source follower device in the buffer stage to be different from the ratio of the source follower device current in the driver stage to its size ratio, making the output V of the driver pole REFOUTP and V REFOUTN with the output of the buffer stage V refp and V refn Not equal, there is a bias voltage, and since the correspondence between the current and the gate-source voltage is temperature-dependent, the offset voltage changes with temperature, resulting in a decrease in the performance and stability of the reference

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