阅读说明：本技术 一种正温电流产生电路 (Positive temperature current generating circuit ) 是由 周泽坤 李世磊 龚州 王卓 张波 于 2021-09-27 设计创作，主要内容包括：本发明属于电源管理技术领域,具体涉及一种正温电流产生电路。本发明的正温电流产生电路实现了在使能控制信号有效的状态下自启动,摆脱简并态,避免了额外启动电路的使用,节省了系统功耗和电路面积。此外,本发明设计的正温电流产生电路隔离了电源电压的噪声影响,提高了电路的电源抑制比和对温度检测的准确性。(The invention belongs to the technical field of power supply management, and particularly relates to a positive temperature current generating circuit. The positive temperature current generating circuit realizes self-starting in the effective state of the enable control signal, gets rid of degenerate state, avoids the use of an additional starting circuit, and saves system power consumption and circuit area. In addition, the positive temperature current generating circuit designed by the invention isolates the noise influence of the power supply voltage, and improves the power supply rejection ratio of the circuit and the accuracy of temperature detection.)

1. A positive temperature current generating circuit is characterized by comprising a PMOS tube, a first triode, a second triode, a third triode, a fourth triode, a first resistor and a second resistor; the source electrode of the PMOS tube is connected with a power supply, the grid electrode of the PMOS tube is connected with an enabling signal, and the drain electrode of the PMOS tube is connected with the collector electrode and the base electrode of the first triode and the base electrode of the second triode after passing through the first resistor; the collector of the third triode is connected with the emitter of the first triode, the base of the third triode is connected with the emitter of the second triode, and the emitter of the third triode is grounded; the base electrode of the fourth triode is connected with the emitting electrode of the first triode, the collector electrode of the fourth triode is connected with the emitting electrode of the second triode, and the emitting electrode of the fourth triode is grounded after passing through the second resistor; the collector of the second triode is the output end of the positive temperature current generating circuit.

Technical Field

The invention belongs to the technical field of power supply management, and particularly relates to a positive temperature current generating circuit.

Background

Temperature is a factor to be considered in chip design, and at different temperatures, device characteristics are different, which causes different working states of a chip system. In comparison, at low temperature or high temperature, the working state of the chip may be abnormal, and if the related temperature detection and over-temperature protection circuit cannot be added during design, the chip may be damaged.

An important ring in the existing chip design is to design a high-precision temperature detection circuit and an over-temperature protection circuit. The design core of the high-precision temperature detection circuit is to generate more accurate positive temperature coefficient (PTAT) voltage, current and negative temperature Coefficient (CTAT) voltage and current.

The common method for generating PTAT voltage current is to use the positive temperature characteristic of the difference of the emitter-base voltages of two BJTs or the positive temperature characteristic of the difference of the source-gate voltages of two MOSFETs working in the subthreshold region, and the common method for generating CTAT voltage current is to use the negative temperature characteristic of the emitter-base voltages of BJTs or the negative temperature characteristic of the source-gate voltages of MOSFETs working in the subthreshold region. Although the core principle of the design of the circuit with temperature characteristics is relatively simple, improving the accuracy of the temperature detection circuit is a relatively challenging research direction.

Disclosure of Invention

In order to solve the problems, the invention provides a self-starting positive temperature current generation circuit with a high power supply rejection ratio.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a positive temperature current generating circuit comprises a PMOS (P-channel metal oxide semiconductor) tube, a first triode, a second triode, a third triode, a fourth triode, a first resistor and a second resistor; the source electrode of the PMOS tube is connected with a power supply, the grid electrode of the PMOS tube is connected with an enabling signal, and the drain electrode of the PMOS tube is connected with the collector electrode and the base electrode of the first triode and the base electrode of the second triode after passing through the first resistor; the collector of the third triode is connected with the emitter of the first triode, the base of the third triode is connected with the emitter of the second triode, and the emitter of the third triode is grounded; the base electrode of the fourth triode is connected with the emitting electrode of the first triode, the collector electrode of the fourth triode is connected with the emitting electrode of the second triode, and the emitting electrode of the fourth triode is grounded after passing through the second resistor; the collector of the second triode is the output end of the positive temperature current generating circuit.

The positive temperature current generating circuit has the advantages that the positive temperature current generating circuit realizes self-starting in the state that the enable control signal is effective, gets rid of degenerated state, avoids the use of an additional starting circuit, and saves system power consumption and circuit area. In addition, the positive temperature current generating circuit designed by the invention isolates the noise influence of the power supply voltage, and improves the power supply rejection ratio of the circuit and the accuracy of temperature detection.

Drawings

Fig. 1 is a schematic diagram of a conventional PTAT current source generation circuit.

Fig. 2 is a schematic diagram of a PTAT current source generation circuit according to the present invention.

Detailed Description

The technical scheme of the invention is described in detail below with reference to the accompanying drawings:

a schematic diagram of a conventional PTAT current source generation circuit is shown in fig. 1, and the PTAT current generation principle is:

the following discusses the problem of the degeneracy point, and the degeneracy point is the first problem, and because the circuit has no current path from the power supply rail VCC to the ground when the enable control signal EN1 is active, the circuit cannot be self-started, and an additional start-up circuit needs to be added. Increasing circuit complexity and system power consumption. Secondly, the triode QN3 and the triode QN4 are respectively positioned in two side branches, the currents passing through the two triodes are not completely equal, and power supply noise and interference signals can be reflected to the current IPTAT1 output by the circuit through the triode QN3, so that the sensitivity of the circuit to temperature changes is reduced.

Fig. 2 shows a schematic diagram of the PTAT current source generation circuit proposed in the present invention, and it can be seen from the diagram that fig. 2 is slightly modified in circuit compared to fig. 1, and no components are added. But the PTAT current source generating circuit provided by the present invention effectively solves the self-starting problem and the problem of large interference from the power supply voltage existing in fig. 1.

The left branch current is determined by the supply voltage VCC and the resistor R3:

and the expression of the right branch current, namely the output temperature coefficient current IPTAT2 is as follows:

since the base currents of transistor QN5 and transistor QN7 are small, the currents flowing through their collectors are approximately equal, i.e.:

V_BE，QN7＝V_BE,QN5

similarly, the currents flowing through the collectors of the triode QN6 and the triode QN8 are approximately equal, the emitter-base voltage difference of the two diodes is irrelevant to the current of the right branch, the generated current IPTAT2 is irrelevant to the voltage VCC of the power supply rail and the resistor R3, and the power supply rejection ratio of the circuit is improved.

When the enable control signal EN2 is active, the circuit generates a current path from the power supply rail VCC, through the MOSFET MP2, the resistor R3, the transistor QN5, the transistor QN8 and the resistor R4 to ground, so that the circuit gets rid of degeneracy during power-on, and self-starting of the circuit is realized.