JPS6157111A - Comparator - Google Patents

Abstract

PURPOSE:To extract any positive or negative phase by constituting a window comparator with a single constant current source so as to reduce power consumption. CONSTITUTION:When an input voltage VIN is lower than a set voltage VL. transistors (TR)Q12, Q14 are turned on, a current from a constant current source 5 flows from the Q12 to the Q14 and an output VOUT of the Q15 goes to L. On the other hand, a Q13 is turned off and an output -VOUT of a Q16 goes to H. When the VIN is between the VL and VH, the Q12, Q13 are turned on, the Q11, Q14 are turned off, the VOUT goes to H and the -VOUT goes to L. When the VIN exceeds the VH, only the Q11 is turned on, the VOUT goes to L and the -VOUT goes to H.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a window type comparator which has a simple circuit configuration using a bipolar transistor circuit and is capable of low current operation.

Conventional configuration and its problems Window comparators determine whether the input voltage value is between two set voltage values.In recent years, with the spread of integrated circuits, It often consists of two integrated operational amplifiers or comparators. Figure 1 shows an example of a configuration consisting of two operational amplifiers 1 and 2 and resistors R1 to R3, and the two voltage settings are vL and vH (vH
), then the input voltage v engineering N is VL < V I N
< VH (7) (!: Output "OUT" at low voltage D, VIN <VL or HVIN>"H @K ■OUT
The voltage is raised to a high voltage, extracted, and used for judgment.

In recent years, as integrated circuits have been used in various fields, it has become desirable to incorporate such functions into integrated circuits as circuit blocks. In the integrated circuit,
What is important in incorporating such a rotation block is that the circuit is simple, does not occupy chip area, and has low power consumption. Therefore, it is often inappropriate to incorporate the circuits of integrated operational amplifiers and comparators into integrated circuits as they are from the viewpoints of the area occupied by the chip and whether the electrical characteristics are sufficient for the requirements. Therefore, a window type comparator as shown in FIG. 2 can be considered. That is, current source 3.4, resistor R4°R5 and transistor 0
1 to Q5, the set voltage v for which the input voltage N is lower
When the voltage is lower than L, transistor Q4 becomes conductive, and the output output from transistor Q, which constitutes an inverting amplifier, is
OUT takes a low voltage. The input voltage N is the set voltage V,
When taking a value between VH and the higher set voltage VH, both transistors Q4 and Q1 are in the cutoff state, so
The output vOUT becomes a high voltage H.

When the input IN is higher than the higher set voltage vH, the transistor Q1 becomes conductive and the output OUT becomes a low voltage. That is, as the input voltage N changes from a voltage lower than the lower set voltage L to a voltage higher than the higher set voltage VH, the output VOUT changes from L-H-L.

Incidentally, one of the disadvantages of this circuit is that two constant current source circuits 3 and 4 must be provided, which results in an increase in current consumption.

Another disadvantage is that when only an anti-phase characteristic that changes from H- to L-H is desired as an output, another stage of inverting circuit must be constructed after the transistor Q5.

OBJECTS OF THE INVENTION An object of the present invention is to provide a window comparator that operates with a single constant current source and has desired phase characteristics with a simple circuit configuration.

Structure of the Invention The present invention can be summarized as follows: first and second transistors each having a current source connected to a commonly connected emitter, and third and fourth transistors each having a collector of the second transistor connected to a commonly connected emitter. comprising a transistor, applying first and second set voltages to the base of the first transistor and the base of the third transistor, respectively;
An input voltage is applied to the base of the second transistor and the base of the fourth transistor, the respective collectors of the first and fourth transistors are connected in common, and the third''! A comparator having an output means attached to the collector of the transistor No. 4 is used. This allows low power consumption and outputs of either forward or reverse phase to be taken out.

DESCRIPTION OF THE EMBODIMENT FIG. 3 shows an embodiment according to the present invention, and the comparison between the set voltage VH and the input voltage vIN is based on the transistor Q.
11jQ12. Transistor Q1
1. The input to the base of Q12 is a diode D1. Given via D2. The emitters of the transestors QiIFQ12 are commonly connected to each other and connected to the current source 5. The comparison between the set voltage VL and the input "IN" is performed by transistors Q13 and Q14 whose emitters are connected to each other and to the collector of the transistor Q12.The collectors of the transistors Q11 and Q14 are commonly connected. ,
The signal taken out here is transmitted to transistor Q1, which constitutes an inverting amplifier. The output is output as voUT.

An output vOUT having an opposite phase to the output vOUT is outputted from the i-rector of the transistor Q13 through the transistor Q16 forming an inverting amplifier.

The embodiment shown in FIG. 3 will be explained in sequence below.

When the input voltage Q12 is lower than the set voltage vL, the transistor Q12. Q14 is not in a conductive state, and the current generated by constant current source 5 flows from transistor Q1° to transistor Q.
14 and makes the output vOUT of the transistor Q16 of the inverting amplifier a low voltage. On the other hand, transistor Q13
Since it is in a cutoff state, the transistor Q1 of the inverting amplifier
6's output ■OUT becomes a high voltage H. Diode D1
is inserted in order to correctly compare the higher setting voltage (H) and the input voltage (N), and it is desirable that it has the same characteristics as the diode D2. When the value of the input voltage N is between the lower set voltage vL and the higher set voltage VH, the transistors Q12 and Q13
conducts, transistor Q11 and transistor Q1
4 is in the cutoff state, so the output vOUT is a high voltage H
Then, the output vOUT will be at a lower voltage. When the value of the input ■IN exceeds the higher set voltage VH, only the transistor Q11 is conductive, so the output ■○UT becomes a low voltage and the inverted output vOUT becomes a high voltage H.

To summarize the above, if the input vIN is lower than vL, then v
As the voltage reaches higher than H, the output vOUT becomes L-
H-L and i-type L, ``OUT changes H-hL-H,!'' Note that the diodes D1 and D2 are as shown in Fig. 4.
PNP) Using transistors Q1□ and Q48, transistors Q11. The input current can be reduced by making a Darlington connection with Q12. In this embodiment, the comparator is a PNP transistor Q11J012,
Although it is constructed using Ql 3 +014, it can also be constructed by replacing it with an NPN transistor and replacing the NPN l-transistor Q151Q16 with a PNP transistor.

Effects of the Invention As described above, according to the present invention, a window type comparator is configured with a single constant current source, and in addition to being able to reduce current consumption, it is also possible to realize any output with a simple circuit configuration. It is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional window comparator, FIG. 2 is a diagram showing a conventional example in which a window comparator is included in a part of an integrated circuit, and FIG. 3 is a circuit according to an embodiment of the present invention. figure,
FIG. 4 is a circuit diagram of a main part obtained by modifying a part of FIG. 3. 1.2...Integrated operational amplifier, 3, 4, 5...
...constant current source circuit, vcc...power supply, vI
N'...Input voltage, VH...First set voltage, VL...Second set voltage, vOUT.
...Output, vOUT...Inverted output of output vOUT, RR..., R1□...Resistor, Dl. 19 2t D2...Diode, Ql,...j
o4P Q'111..., Q18...
・Transistor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 3 Figure 4

Claims (1)

[Claims] the first and second with a current source connected to the emitters of the common connection;
a transistor, third and fourth transistors having a collector of the second transistor connected to a commonly connected emitter, and a base of the first transistor and a base of the third transistor have a first and a second
applying a set voltage to each of the bases of the second transistor and the base of the fourth transistor, respectively connecting the collectors of the first and fourth transistors in common; A comparator configured to take out an output from the collector of the third or fourth transistor.