Current control type low-pressure drop voltage-stabilizing circuit

Abstract

The invention relates to a low-pressure drop voltage-stabilizing circuit which has very wide application in various forms of electronic systems. The traditional low-pressure drop voltage-stabilizing circuit samples output voltage by a resistor in proportion and limits the transient response performance and the control precision of a loop by adopting voltage type feedback and calculation. The invention discloses a current-type loop control technology used for a low-pressure drop integrated regulator, which directly samples the output voltage by using an active voltage buffer, generates control current by utilizing a transconductance amplifier and generates the control voltage output voltage of a power transistor by an integrating filter, which can effectively improve the response speed and the control precision of the loop. A circuit frame of a current type control method disclosed by the invention comprises a voltage sampling module, the transconductance amplifier, a reference current source, the integrating filter 3 and a power output stage 5 and carries load off chip.

Description

technical field [0001] The invention belongs to the field of integrated circuit design and is used for low-drop voltage stabilizing integrated circuits, in particular to a voltage stabilizing structure that uses current signals to form a control loop to control output voltage. Background technique [0002] The power supply system plays an important role as the basis of modern electronic systems, and the stability of the power supply directly determines the performance of the electronic system. In the field of low-voltage power supply, a low dropout regulator (LDO) circuit has been widely used because of its relatively simple structure, small power supply ripple and good dynamic performance. [0003] For LDO, control accuracy and dynamic response capability are the most important performance indicators. figure 1 It is a classic LDO structure, the resistors R0 and R1 sample the output voltage proportionally, the amplifier OP compares the sampled voltage signal with the refere...

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Problems solved by technology

However, figure 1 There are several deficiencies in the LDO structure shown, which will seriously affect the accuracy and dynamic response of the output voltage:

[0004] 1. Relying on resistance sampling, especially relying on external resistance sampling, the sampling accuracy depends heavily on the matching degree of resistance R0 and R1. Generally speaking, resistance devices lack sufficient consistency, especially the accuracy of discrete resistance components is difficult to guarantee the feedback voltage It has a certain proportional relationship with the output voltage, which affects the consistency of the output accuracy;

[0005] 2. The actual output load is the parallel connection of the external load and the sampling resistor network, so the sampling response is greatly affected by the load, which limits the dynamic response capability of the system;

[0006] 3. Usually the LDO uses a Bandgap Voltage Reference (BGR) to generate a reference voltage. The output of the BGR is stable at 1.23V. After the LDO output voltage is stable, the feedback voltage after the resistor network divides the voltage cannot be lower than this value. It also limits the LDO output lower voltage

Although theoretically speaking, proportional control can make the loop have better output accuracy, but pure proportional control is limited by the proportional accuracy of feedback, and it is difficult to obtain better results in output overshoot and settling time

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