Miscellaneous active electrical nonlinear devices – circuits – and – External effect – Temperature
Reexamination Certificate
1999-08-04
2001-07-03
Lam, Tuan T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
External effect
Temperature
C327S513000
Reexamination Certificate
active
06255891
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a temperature detecting circuit, a temperature detecting method and a photo-electric conversion apparatus which are constituted, in particular, on a semiconductive substrate.
2. Brief Description of the Related Art
FIG. 7
(PRIOR ART) is a circuit diagram illustrating a conventional constitution of a temperature detection circuit for taking a temperature of a semiconductor substrate. This circuit is constituted of a bipolar transistor Q
11
embedded in the semiconductor substrate and a constant current source
11
for flowing a constant current I
11
which is connected between a collector electrode of the transistor Q
11
and a direct current (referred to as “DC” hereinafter) voltage source Vcc.
In the circuit constituted as mentioned above, the constant current source
11
feeds the constant current I
11
to a diode which constitutes the transistor Q
11
, thereby to generate a forward bias voltage Vf. This forward bias voltage Vf has a temperature characteristics corresponding to the temperature of the semiconductor substrate. Accordingly, one can detect the temperature of the semiconductor substrate from this temperature characteristics.
However, in the conventional example as mentioned above, there exist various problems such as a variance in absolute value of the forward bias voltage Vf of the transistor Q
11
which is induced by dispersion in device manufacturing parameters, another variance in the forward bias voltage Vf which is invited by a variation in constant current I
11
which is inherent to a performance in constant current characteristics of the constant current circuit
11
and still another variance in temperature characteristics of the transistor Q
11
which is introduced by a temperature-dependent variation of the constant current source
11
.
Consequently, it is intended to supply the constant current from an external source to eliminate the variances in the constant current I
11
. However, this intention increases a terminal number and, further, a number of external components, which encounters another problem of an excessive manufacturing cost.
Furthermore, in a case when the circuit is fabricated by using a Complementary Metal Oxide Semiconductor (referred to as “CMOS”) device manufacturing process, one of electrodes of the diode is fixed either to a supply voltage or to a grounding potential because of the manufacturing process steps, which results in still another problem that a restriction in output voltage takes place.
On the other hand, in another case when a photo-electric conversion device (referred to as “photosensor” hereinafter) is fabricated on the semiconductor substrate, dark current characteristics which is inherent to the photosensor cannot be neglected and appears as a fixed pattern noise. As a correction measures of the fixed pattern noise, it is proposed to fabricate above-mentioned temperature detection circuit on the same substrate as that the photosensor is formed in, thereby to compensate the pattern noise by using the temperature. However, the correction or the compensation itself not only is unexpectable in precision as well as by cost due to the previously cited problems but also brings about further still another problem that it imposes excessively a restriction on species of employable devices because the device manufacturing processes are limited to that of the photosensor device.
SUMMARY OF THE INVENTION
The present invention is carried out to solve the problems mentioned above. An object of the invention is to provide a temperature detection circuit and a temperature detection method which are immune against a dispersion in manufacturing parameters even when they are constituted at a reduced cost.
Another object of the invention is to constitute all of the circuits in a single substrate, thereby to provide further advantageous temperature detection circuit and temperature detection method at an economical production cost.
Still another object of the invention is to fabricate the temperature detection circuit in the same substrate as that of a photo-electric conversion device, thereby to provide a photo-electric conversion apparatus which is excellent in temperature characteristics.
To satisfy above-mentioned purposes, temperature detection circuits according to the present invention are constituted as follows:
(1) A temperature detection circuit comprises:
two rectification means each having a rectifying characteristics which are connected in parallel to each other; and
a temperature detection mean for taking a temperature from a temperature characteristics of a differential voltage between two respective voltages which are generated by applying a current density ratio to the two rectification means.
(2) The temperature detection circuit described in (1) is further constituted, wherein:
the rectification means include a bipolar transistor; and
the detection means takes the temperature from the temperature characteristics of the differential voltage between respective voltages across respective emitter-base junctions which are generated by applying the current density ratio to the two bipolar transistors.
(3) A temperature detection circuit comprises:
a first bipolar transistor of which collector is connected to a DC voltage source, of which base is connected to a reference voltage source having no temperature-dependent characteristics and of which emitter is connected both to a first constant current source and to one of input terminals of an operational amplifier; and
a second bipolar transistor of which collector is connected to the DC voltage source, of which base is connected to an output terminal of the operational amplifier and of which emitter is connected both to a second constant current source and to another of the input terminals of the operational amplifier, wherein:
a temperature characteristics is obtained from an output produced from the operational amplifier.
(4) The temperature detection circuit described in (3) is further constituted, wherein:
the first bipolar transistor and the second bipolar transistor are formed in a single semiconductor substrate.
(5) The temperature detection circuit described in (3) is still further constituted, wherein:
an emitter size of the first bipolar transistor is enlarged larger than that of the second bipolar transistor; and
a current value fed from the second constant current source is enhanced higher than that fed from the first constant current source, thereby to apply an emitter current density ratio to the two transistors.
(6) The temperature detection circuit described in (3) is more still further constituted, wherein:
a gain of the operational amplifier is enhanced higher, thereby to produce a large voltage output for detecting enough the temperature characteristics.
To satisfy above-mentioned objects, a method of detecting a temperature according to the present invention is constituted as follows:
(7) A method of detecting a temperature comprises steps of:
fabricating two bipolar transistors connected in parallel to each other on a single semiconductor substrate;
applying a current density ratio to respective emitter electrodes of the two bipolar transistors; and
detecting a temperature of the semiconductor substrate from a temperature characteristics of a differential voltage between the two respective emitter-base voltages which are generated by the step of applying the current density ratio to the two emitter electrodes.
To satisfy above-mentioned purposes, photo-electric conversion apparatus according to the present invention are constituted as follows:
(8) A photo-electric conversion apparatus formed on a single semiconductor substrate comprises:
a photosensor device for converting an incident optical signal into an electric signal;
a temperature detection circuit, including:
two rectification means each having a rectifying characteristics which are connected in parallel to each other and
a detection means for detecting a temperature from a temperature characteristics of a di
Matsuno Yasushi
Shinohara Mahito
Canon Kabushiki Kaisha
Lam Tuan T.
Morgan & Finnegan , LLP
Nguyen Hiep
LandOfFree
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