Mitsubishi Denki Kabushiki Kaisha

Osamu Kaneta

Susumu Takahashi

Masashi Ueno

Norio Ookawa

Circuitry for a bolometer-type image pickup device improves the signal-to-noise ratio and reduces variations of an output offset level due to temperature variations of the device. A clamp voltage is applied to an amplifier 18 via a clamping diode 36 connected thereto. This reduces a difference between an input voltage during an off-state of one of horizontal FET switches 9, 10, and an input voltage during the off-state of both horizontal FET switches 9, 10, thereby improving a signal-to-noise ratio by narrowing a frequency band of an external circuit. Further, a variable load resistor 43 whose resistance varies with temperature similarly to those of bolometers 1-4, a resistance of a pseudo resistor 44 which is substantially equal to a sum of conductive resistances of vertical FET switches 1, 14 and horizontal FET switches 9, 10, and a compensating diode 45 whose forward bias voltage varies with temperature similarly to those of pixel separating diodes 39-42 are connected in series between the horizontal FET switches 9, 10 and a bias current output terminal 12, thereby offsetting variations of an output offset level due to temperature variations.

Growing community of inventors

Amagasaki, Japan

Osamu Kaneta