Digital thermometer

Abstract

Abstract PURPOSE:To dispense with a reference voltage source and to reduce the power consumption by driving a DC amplifier, which is composed of a performance load calculating amplifier for generating a voltage according to a temperature, and a reference voltage generating circuit for A/D conversion with the use of an identical power source. CONSTITUTION:A C-MOS inverse calculation amplifier 1 of an active load, which is connected with a feedback resistor R3, is driven by a DC power source V1 thereby to generate a voltage according to the temperature with a small power consumption through a thermister 2 which has its resistance varying in accordance the temperature. On the other hand, the reference resistors 8 to 12, which are interchanged consecutively through a multi-vibrator 20 and a ring counter and which are connected with switches 3 to 7, generate reference voltages in response to the power supply from the identical power source V1 so that the output voltage of the amplifier 3 is digitally converted in a non-linear manner through a calculating amplifier 13 using an active load and a comparator using an active load. As a result, by the use of a display element using a liquid crystal, the temperature is displayed with a small power consumption without any use of the A/D conversion reference power source.

Inventors

• 👤 Katsumi Yamamura
• 👤 Katsuyuki Ikeda

Bibliographic Details