Illumination sensor
AssigneeRohm Co., Ltd.
InventorsShinichi Otsuka, Yuichiro Nakata, Junji Fujino
Life of this patent
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Abstract
In an ambient light sensor according to the present invention, a current amplification portion which amplifies a light current obtained by a light receiving portion to generate an output signal includes: a current amplification stage that has: a first current mirror amplifier which is composed of a bipolar transistor, and a second current mirror amplifier which is composed of a field effect transistor connected in parallel with the first current mirror amplifier; and a changeover control circuit which monitors an amplified current input into the current amplification stage, and performs changeover control of the first and second current mirror amplifiers according to a value of the amplified current.
Claims8
An ambient light sensor, comprising:
- a light receiving portion which generates a light current that depends on ambient illumination;
- and
- a current amplification portion which amplifies a light current obtained by the light receiving portion to generate an output signal,
- wherein the current amplification portion includes:
- a current amplification stage that has:
- a first current mirror amplifier which is composed of a bipolar transistor, and a second current mirror amplifier which is composed of a field effect transistor connected in parallel with the first current mirror amplifier;
- and
- a changeover control circuit which monitors an input current to the current amplification stage, and performs changeover control of the first and second current mirror amplifiers according to a value of the input current.
Dependencies are inferred from the claim text.