Bandgap voltage reference circuit with start-up circuit

Abstract

The invention discloses a bandgap voltage reference circuit with a start-up circuit. In the start-up circuit, a comparator is used for comparing a resistance value of a first resistor which is connected with the bandgap voltage reference circuit in series and has positive and negative temperature coefficients and the voltage drop on a second resistor the same as the first resistor, so that when the voltage drop is the same, the current of a first P-channel metal oxide semiconductor (PMOS) tube of the current source of the device is increased, and the problem that the device cannot be opened is solved. In addition, the start-up circuit also can eliminate the zero state of the bandgap voltage reference circuit, and can automatically be closed when the bandgap voltage reference circuit normally works so as not to influence the normal work of the bandgap voltage reference circuit.

Description

technical field [0001] The invention relates to a bandgap voltage reference circuit. More particularly, it relates to a bandgap voltage reference circuit with a start-up circuit. Background technique [0002] Bandgap voltage reference circuits are widely used in storage circuits, analog-to-digital conversion circuits and power management circuits, and their function is to generate a constant voltage value that does not vary with temperature, process and voltage. The bandgap voltage reference circuit usually uses devices with positive temperature coefficient and negative temperature coefficient characteristics to adjust the parameters of the device so that the absolute values ​​of the positive temperature coefficient and negative temperature coefficient of the entire bandgap voltage reference circuit are the same, so that the entire bandgap voltage The temperature coefficient of the reference circuit is zero. [0003] In the bandgap voltage reference circuit, two common-gat...

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Problems solved by technology

[0032] However, in figure 2 In the bandgap reference voltage circuit 20, since the branch where the bipolar transistors Q21 and Q22 are located is connected in parallel with resistors, there may also be such a state that when the PMOS transistors M21 and M22 as current sources start to provide current and operation When the amplifier OP2 can work, the voltage at the nodes A and B cannot turn on the bipolar transistors Q21 and Q22

Because there are resistors R23 and R24 connected in parallel on the branches with Q21 and Q22, the current will all flow through the resistors R23 and R24, and if the start-up circuit is closed at this time, the entire bandgap reference voltage circuit 20 will maintain this state, thus Bandgap voltage reference circuit 20 not working properly

Therefore, when a resistor is connected in parallel to the branch of the device with positive and negative temperature coefficients in the bandgap voltage reference circuit, a circuit structure is needed to solve the problem that the device cannot be started

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