Off-chip capacitor LDO circuit based on self-adaptive power tube technology

Abstract

The invention discloses an off-chip capacitor LDO circuit based on the self-adaptive power tube technology.The circuit comprises a control voltage generation unit, a first-stage amplifier, a second-stage amplifier, a frequency compensation unit, a main power tube and an auxiliary power tube.The control voltage generation unit is used for generating control voltage Vctrl; the first input end of the first-stage amplifier is electrically connected with the output end of an LDO, the second input end of the first-stage amplifier is connected with the output end of the control voltage generation unit, the output end of the first-stage amplifier is electrically connected with the input end of the second-stage amplifier, the first end of the frequency compensation unit and the grid electrode of the auxiliary power tube respectively, the grid electrode of the main power tube is electrically connected with the output end of the second-stage amplifier, the main power tube and the source electrode of the auxiliary power tube are connected with a power source, the drain electrodes of the main and auxiliary power tubes and the second end of the frequency compensation unit are electrically connected with the output end of the LDO, and the main power tube is automatically turned on or off according to the load.The off-chip capacitor LDO circuit has the advantages of being low in working voltage, low in no-load current, high in loop gain and wide in output drive range.

Description

technical field [0001] The invention relates to the field of LDO circuits, in particular to an LDO circuit without external capacitors based on adaptive power tube technology. Background technique [0002] With the popularization of portable devices such as tablets and smart phones, people have higher and higher requirements for battery life, and quiescent current and low input-output voltage difference are particularly important. Low dropout linear regulator (LDO) has the advantages of low static power consumption, low noise, relatively simple circuit structure, few peripheral components, and small circuit scale, so it can be widely used in portable electronic products. [0003] The circuit structure of a traditional LDO is as figure 1 As shown, it is necessary to add an additional off-chip capacitor at the output end, and the value of the capacitor reaches the μF level. The off-chip capacitor also has relatively serious defects. Its size is too large to be integrated in ...

AI Technical Summary

Problems solved by technology

Most of the current compensation schemes have minimum load current requirements, and it is difficult to be stable under no-load conditions. Therefore, it is necessary to study compensation schemes with a wide output drive range.

Images