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Linear voltage regulator and current sensing circuit thereof

A linear voltage regulator and current sensing technology, applied in the direction of measuring current/voltage, instruments, measuring devices, etc., can solve the problems of large frequency variation of non-dominant poles and insufficient phase margins

Inactive Publication Date: 2012-03-14
NOVATEK MICROELECTRONICS CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] However, the pass transistor M NO The transduction gm will vary with the load current I LOAD and change, causing the frequency of non-dominant poles to vary too much
The fixed zero frequency cannot effectively cancel each other out with the non-dominant pole frequency at the output end, at different load currents I LOAD However, there will still be situations where the phase margin is insufficient

Method used

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  • Linear voltage regulator and current sensing circuit thereof
  • Linear voltage regulator and current sensing circuit thereof
  • Linear voltage regulator and current sensing circuit thereof

Examples

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Effect test

no. 1 example

[0054] Please refer to Figure 4 , Figure 4 Shown is a schematic diagram of the architecture of a linear regulator. The linear regulator 40 is, for example, a high drop out (High Drop Out, HDO) linear regulator. The linear regulator 40 includes a pass transistor M NO , compensation capacitor C C , feedback circuit 41, error amplifier A 1 , a variable resistor 42 and a current sensing circuit 43 . For the sake of illustration, Figure 4 The pass transistor M shown NO Taking N-type metal-oxide-semiconductor (Metal-Oxide-Semiconductor, MOS) transistor as an example, the type of transfer transistor is not limited to this, and P-type metal-oxide-semiconductor transistors, NPN bicarrier junction transistors ( BipolarJunction Transistor, BJT) or PNP bipolar junction transistor.

[0055] pass transistor M NO The first terminal receives the input voltage V IN , the transfer transistor M NO The second terminal outputs the output voltage V OUT . pass transistor M NO The fi...

no. 2 example

[0064] Please refer to Figure 6 , Figure 6 Shown is a circuit diagram of the linear regulator of the second embodiment. In the second embodiment, the linear voltage regulator 40, the variable resistor 42 and the current sensing circuit 43 are respectively the linear voltage regulator 40(2), the variable resistor 42(2) and the current sensing circuit 43(1) As an example. The main difference between the second embodiment and the first embodiment lies in the variable resistor 42(2). The variable resistor 42(2) except the aforementioned transistor M N2 additionally, including transistor M N3 . Transistor M N3 The first end and the second end of the transistor M are such as the drain and the source respectively, and the transistor M N3 The control terminal of is, for example, the gate. Transistor M N3 The first terminal of is coupled to the transistor M N3 The control terminal and the transistor M N3 The second terminal is coupled to the compensation capacitor C C and...

no. 3 example

[0067] Please refer to Figure 7 , Figure 7 Shown is a circuit diagram of the linear regulator of the third embodiment. In the third embodiment, the linear voltage regulator 40, the variable resistor 42 and the current sensing circuit 43 are respectively the linear voltage regulator 40(3), the variable resistor 42(3) and the current sensing circuit 43(2) As an example. The main difference between the third embodiment and the second embodiment lies in the variable resistor 42(3) and the current sensing circuit 43(2). The current sensing circuit 43(2) further includes a transistor M N2 , transistor M N2 It is coupled between the variable resistor 42(3) and the ground. Transistor M N2 The control terminal is coupled to the operational amplifier A 2 The output terminal, and the transistor M N2 Controlled by the op amp A 2 . Variable resistor 42(3) includes only transistor M N3 . Transistor M N3 The first end and the second end of the transistor M are such as the drai...

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Abstract

The invention discloses a linear voltage regulator and a current sensing circuit thereof. The linear voltage regulator comprises a pass transistor, a compensation capacitor, a variable resistor, an error amplifier and a current sensing circuit, wherein the current sensing circuit comprises a sensing transistor and a voltage lock; the sensing transistor is controlled by the error amplifier; the first end of the sensing transistor receives input voltage; the sensing transistor is used for generating a sensing current which is related to transmission current flowing through the pass transistor; the voltage lock is coupled with the second end of the pass transistor and the second end of the sensing transistor, and controls the voltage of the second end of the pass transistor to be equal to the voltage of the second end of the sensing transistor; and the voltage lock regulates the variable resistor coupled with the compensation capacitor according to the voltage of the second end of the pass transistor and the voltage of the second end of the sensing transistor.

Description

technical field [0001] The present invention relates to a linear voltage regulator and its current sensing circuit, and in particular to a linear voltage regulator with Pole-Zero Tracking function and its current sensing circuit. Background technique [0002] Please refer to figure 1 , figure 1 Shown is the circuit diagram of the first conventional linear regulator. A conventional linear regulator 10 includes a pass transistor M NO , compensation capacitor C C , feedback circuit 41 and error amplifier A 1 . pass transistor M NO The first terminal receives the input voltage V IN , the transfer transistor M NO The second terminal outputs the output voltage V OUT to the load. pass transistor M NO The first terminal and the second terminal are respectively the drain and the source. The feedback circuit 41 is coupled to the error amplifier A 1 The inverting input of the pass transistor M NO Between the second terminals, the feedback circuit 41 further includes a res...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05F1/56G01R19/00
Inventor 林永正
Owner NOVATEK MICROELECTRONICS CORP
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