The voltage outputs of the temperature-sensing diodes are applied to a standard difference amplifier, which in turn outputs the difference voltage that will vary from -20 V to 0 V as the difference temperature rises from 0°C to 10 °C
Figure 2. The voltage outputs of the temperature-sensing diodes are applied to a standard difference amplifier, which in turn outputs the difference voltage that will vary from -20 V to 0 V as the difference temperature rises from 0°C to 10 °C