CN104062999A - Self-starting high-matching band-gap reference voltage source chip design - Google Patents

Abstract

The invention discloses a novel self-starting high-matching bandgap reference voltage source chip design circuit. On the one hand, the circuit can ensure that the power supply can be started safely each time, and prevent the zero solution of the circuit balance equation under extreme circumstances from causing the reference voltage On the other hand, compared with the traditional circuit, the improved circuit of the present invention effectively overcomes the channel modulation effect of the mirror current source, the circuit structure has better matching characteristics, and the output voltage consistency is better than that of the traditional circuit. The solution is better.

Description

Design of self-starting high-matching bandgap reference voltage source chip

technical field

The invention belongs to the technical field of analog integrated circuit design, and the technology can be used to generate a high-precision and high-reliability reference voltage source inside the integrated circuit.

Background technique

The rapid development of integrated circuit technology, especially the rapid progress of SOC system-on-chip technology, requires that a high-reliability and high-precision reference voltage source must be integrated inside the integrated circuit. The impact of different batches of processing technology changes to ensure stable and reliable circuit performance. The accuracy and reliability of the traditional reference voltage source design technology basically meet the design requirements in general applications. However, for the occasions with extremely high performance requirements such as aerospace or biology, the traditional voltage source circuit still has problems that cannot be started and The problem of insufficient precision. Especially the problem of self-starting of the circuit. Theoretically, there are zero and non-zero double solutions of the current balance equation. Under extremely accidental probability conditions, once the current equation obtains a zero solution, the voltage source will have the risk of being unable to start, resulting in the failure of the entire chip. The work may have a fatal impact on the system, so it is necessary to consider increasing the self-starting circuit design to strengthen the circuit's ability to resist deadlock. On the basis of the traditional reference voltage source, the present invention further improves the reliability of safe start-up through two circuit improvements and at the same time effectively suppresses the channel modulation effect of the current source and improves the output voltage precision.

Contents of the invention

On the basis of the core circuit of the traditional bandgap reference voltage source, the invention adds a self-starting circuit and improves the matching characteristics of the circuit. The technical improvement of the self-starting high-matching voltage source of the present invention is characterized in that: (1) on the opposite side of the output branch of the bandgap reference voltage source, a matching resistor is added to reduce the channel modulation of the PMOS current source MP1 and MP2 (2) In addition to the core circuit, an additional voltage source startup circuit is added to ensure that the core circuit of the voltage source must start every time it is powered on to prevent no output voltage that may be caused by circuit deadlock occurrence of the situation.

The main features of the program are:

1. The matching enhancement scheme is simple and effective. Please refer to Figure 2 of the manual. Adding a resistor on the left loop of the op amp that is the same as the right loop can suppress the channel caused by the unequal source-drain voltage of the PMOS current source MP1 and MP2. The occurrence of the modulation effect reduces the mismatch current of the left and right current source branches, so that the currents I ₁ and I ₂ on the left and right sides are closer to equal, and the zero temperature coefficient output voltage is more ideal.

2. In addition to the core circuit, three MOS devices as shown in Figure 2 of the specification are added, and the self-starting of the circuit is realized every time the circuit is powered on. At the beginning of power-on, because the PMOS device MP3 is turned on, and when the gate voltage of MN1 rises above the turn-on voltage, MN1 is turned on, and the turn-on of MN1 will pull down the gates of MP1 and MP2, so that MP1 and MP2 are turned on to generate current and thus break away from the Possible zero solution, so every time the circuit is powered on, the improved core circuit must start. In addition, once the reference voltage source circuit starts, the output voltage will be stable around 1.2V, and the voltage will be sent to the gate of the MN2 tube while outputting , Turning on MN2 makes its drain voltage drop, thereby disconnecting MN1, so as to achieve the purpose of disconnecting the self-starting circuit and the core circuit after the output voltage is available, and avoid the influence of the self-starting circuit on the core circuit.

Description of drawings

Figure 1 is the core circuit of the bandgap reference voltage source.

Figure 2 is an improved circuit of self-starting high-matching bandgap reference voltage source.

Detailed ways

The technical implementation plan is that in addition to the core circuit of the reference voltage source, a self-starting circuit for guiding the output current source circuit to be turned on every time when the power supply is powered on, and a matching resistance scheme to improve circuit consistency, high matching characteristics The specific implementation methods obtained are: (1) On the basis of the traditional reference voltage source, matching resistors of the same size are set on both sides of the op amp feedback loop, so as to reduce the current source on both sides of the op amp being modulated by the channel The current mismatch caused by the effect. The specific implementation of the self-starting scheme is as follows: (1) the scheme uses a diode-connected PMOS transistor MP3 to charge, so that the NMOS transistor MN1 can be turned on normally every time; (2) the drain of the NMOS transistor MN1 is connected to the gate of the output current source pole, the source is grounded, and the gate voltage of the PMOS current source is pulled down instantaneously through its conduction during use, making it work and output a certain current, thereby generating an output voltage and finally stabilizing at around 1.2V; (3) NMOS tube MN2 Its gate is connected to the output reference voltage, its drain is connected to the gate of the MN1 tube, and its source is grounded. The purpose is to turn on MN2 by using the voltage generated by the reference output voltage source every time. The opening of MN2 can turn off MN1, thereby The self-starting circuit is separated from the core circuit to avoid the influence of the starting circuit on the core circuit when it is working normally.

Claims (3)

1. Self-starting high-matching bandgap reference voltage source design technology, its main features are: the overall scheme includes a voltage source starting circuit, and a matching resistance circuit intentionally added to improve the voltage output consistency. 2. according to claim 1, the high matching characteristic of novel bandgap reference voltage source, its main feature is: on the basis of traditional reference voltage source, on the other side of the operational amplifier loop relative to the output reference voltage branch , adding a resistor sized to exactly match the output side. 3. According to claim 1, the novel bandgap reference voltage is derived from the start-up characteristic, and its main feature is: outside the reference voltage source core circuit, an automatic switch for guiding the output current source circuit to be opened when the circuit is powered on is designed in addition. The start-up circuit, its main features are as described in Figure 2 of the manual, specifically: (1) the scheme uses a diode-connected PMOS transistor MP3 to charge, so that the NMOS transistor MN1 can be turned on normally every time; (2) the NMOS transistor MN1 The drain is connected to the gates of the output current sources MP1 and MP2, and the source of MN1 is grounded; (3) The gate of the NMOS tube MN2 is connected to the output reference voltage, and its drain is connected to the gate of the MN1 tube, and the source is grounded. The reference output voltage source can turn off MN1 after each voltage is generated, so that the self-starting circuit is separated from the core circuit, and the influence of the start-up circuit on it when the core circuit is working normally is avoided.