JPS6096006A - Reference voltage circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a reference voltage circuit, in particular, a reference voltage circuit that can set the change in output voltage due to temperature to zero or an arbitrary value, and at the same time set an arbitrary output voltage value. Regarding reference voltage circuits that can be used.

Conventional configurations and their problems At present, the mainstream reference voltage circuit is the well-known configuration known as the Nokundogyanop method.In order to obtain an arbitrary output voltage value in a semiconductor integrated circuit, the standard voltage circuit shown in Fig. 1 is usually used. The first . Second. A third resistor i(,, R2,i(3) is inserted, and the first and second transistors Q1... of current mirror coupling operate at different current densities.
The difference in voltage between the base and emitter of Q2 is taken out by the third resistor R3, and this voltage with a positive temperature coefficient is applied to the second resistor H.
2 and has a negative temperature coefficient, the base-emitter voltage of the third transistor Q3 is
A reference voltage having a temperature coefficient of zero or an arbitrary value is generated, and this voltage is applied to the voltage #r0. J-hi 1
:1 current mirror circuit to obtain an arbitrary output voltage by dividing the resistor M4,1 (6).

However, in the case of the conventional bandgap reference voltage circuit shown in FIG. 1, the reference voltage value and its temperature coefficient cannot be adjusted independently, so an extra high voltage is required.

For example, even if the reference voltage ref = 0.6V is required, the reference voltage must be at least twice the base-emitter voltage BE of the bipolar transistor, that is, 1.1 to 1.3V. For this reason, a minimum of 2 to 3 V is required as the power supply voltage.Also, since the output vref-3V is required, the reference voltage is 3.7 to 3 V.
3.9V.

A power supply voltage of 4.5 to 5.5V is required. In the recent trend toward lower power supply voltages, the need for such an extra high voltage is a disqualifying factor.

Furthermore, it is difficult to reduce current consumption using conventional methods; for example, in the circuit shown in Figure 1, if we rely on normal semiconductor integrated circuit manufacturing, there is a limit to the increase in resistance due to the large area occupied. It is practically difficult to achieve a high resistance circuit of 600 μA or less.

Purpose of the Invention The present invention aims to reduce power supply voltage and current consumption in each chapter.
Furthermore, the present invention provides a reference voltage circuit that can easily set an arbitrary temperature coefficient and an arbitrary output voltage value.

Configuration of the Invention In summary, the present invention has a first and a second current source each having a collector connected to the first and a second transistor operating at different current densities, and a base to the first current source. The emitter circuit of the third transistor connected to the first. A second resistor is connected in series to the base of the first transistor. A voltage is applied to the connection midpoint of the second resistor, and an emitter potential of the third transistor is applied to the base of the second transistor.
A third resistor is connected to the emitter circuit of the transistor,
A fourth resistor connected to the third current source is connected to J! ! This is a reference voltage circuit equipped with a configuration that takes out the output at the same time, thereby obtaining a temperature-compensated low reference voltage between the third resistor terminals, which is then applied via a tilt mirror coupling. A low reference voltage output can be obtained from the fourth resistor.

DESCRIPTION OF THE EMBODIMENTS FIG. 2 is a circuit diagram of an embodiment of the present invention, and the present invention will be explained in detail with reference to this practical example.

In FIG. 2, the first transistor Q21 and the second transistor Q22 have a first resistor R21 and a second resistor R221/(therefore, their respective base potentials are connected to the emitter circuit of the third transistor Q23). In addition, a transistor Q is provided at the collector of each of the first transistor Q21 and the second transistor Q22.
24 and Q25 are respectively connected to the first and second current sources by the current mirror circuit, and further,
The base of the third transistor Q23 is also connected to the first current source transistor Q24, while the emitter path of the second transistor Q22 is connected to the third resistor R23. The reference voltage output vref is then taken from a fourth resistor R24 connected to a third current source, another current mirror coupled transistor Q26.

Analytically speaking, the operation of this circuit is expressed by equation (1), where the emitter voltage of the second transistor 022 is ignored and the base current of each transistor is ignored.

...(1) If the base-emitter voltage difference △vBE between transistors Q21 and 022 is included in the first term on the right side of equation (1), and if this base-emitter voltage difference Δvk3E, then each transistor Q24 of the current mirror circuit , Q25, and the operating currents I, , I, supplied at a constant ratio by the transistors Q21 . Q
It is determined by the emitter area ratio of 2°.

This is expressed in equation (2).

J J :) Ransistor Q21. Operation type 11 of Q22
2 Current density S・ , S・: transistor Q21. Q22 Emi J
! , I J! , 2 Ivy area ratio n: Current mirror operating current ratio I, /I.

k: Boltzmann's constant q: Electronic constant T: Absolute temperature (0K) Here, the temperature coefficient of voltage vs. It will be done.

The first term on the right side of equation (3) is a positive value, the second term is a negative value, and by adjusting the resistance ratio H22/R21, the zero temperature coefficient or f/'r can be set to an arbitrary temperature coefficient. I know what I can do. Here, the temperature compensated voltage vs is the transistor Q21. It is constant depending on the operating current density ratio of Q22, and is generally a value of 0.5 V or less, and this is applied to the current mirror circuit transistor Q25. It is sufficient to convert it into a voltage drop across the resistor R24 using Q2'6 and take it out as the reference voltage vref. Finally, the value of the reference voltage vref and its temperature coefficient are expressed by the valleys (4v equation, (6) equation).

(m: Operating current ratio I of current mirror Q26''26, /I
, ) Regarding the setting of the zero temperature coefficient, see Q21. It is only necessary to adjust the operating current density ratio of Q22 and the resistance ratio '22/'21, and any reference voltage value can be obtained by further adjusting the resistance ratio '24/kL23.

According to the embodiment circuit of the present invention, the reference voltage output vref only needs to be lower than the power supply voltage by the saturation voltage difference of the transistor Q26. Therefore, the supply voltage should be at least 2”
Since it operates from a voltage of BE+1vCE (SAT), that is, approximately 1.6v in practice, for example, a reference voltage of 0.5
Power supply voltage 1. If the power supply voltage is 3.2V with respect to rs V and the reference voltage of 3V, it will operate stably and it will be easier to lower the power supply voltage compared to conventional bandgap reference voltage circuits.

Unfortunately, it is easy to reduce the /l'i cost current, and the operating current of each current mirror circuit can be set to about 20μ8, so even if you estimate the maximum current, it is possible to suppress the current consumption to less than 100μ8. It is possible.

At the same time, as is clear from equations (4) and (6), △■
The transistor Q21゜Q2 determines j:lE.
Since only the emitter area ratio of 2 and the current ratio of the current mirror circuit and the reference voltage setting is only the resistance ratio, it has higher accuracy than conventional circuits and is ideal for semiconductor integrated circuit devices.

Effect of the invention According to the present invention, there are the following effects.

The first effect is that it is easy to lower the power supply voltage.

The second effect is that low consumption flow can be achieved easily.

The third effect is high accuracy.

At the same time as having this effect, with only three resistance ratios,
It is ideal for semiconductor integrated circuits because any temperature coefficient and any reference voltage value can be easily set.

[Brief explanation of drawings]

FIG. 1 is a reference voltage circuit diagram of a conventional bandgap method, and FIG. 2 is a reference voltage circuit diagram of an embodiment of the present invention. Q −Q ...transistor, R21 to R24
...21 26 Resistance.

Claims (2)

[Claims] (1) First and second transistors operating at different current densities are connected to the collectors of the first and second current sources, respectively, and a third transistor whose base is connected to the first current source is connected to the first and second current sources. The first one is in the emitter circuit. A second resistor is connected in series to the base of the first transistor. Applying a connection midpoint potential of a second resistor, applying an emitter potential of the third transistor to the base of the second transistor, and connecting a third resistor to the emitter circuit of the second transistor. , a reference voltage circuit configured to take out an output through a fourth resistor connected to a third current. (2) First. The reference voltage circuit according to claim 1, wherein the second and third valley current sources are current mirror coupled to each other.