An improved current-mode CMOS voltage reference

An improved current-mode CMOS voltage reference derives its temperature independent characteristic from two temperature dependent currents which are summed together into a resistor to generate the reference voltage. A CMOS proportional to absolute temperature (PTAT) current generator using substrate bipolar transistors creates the current that increases with temperature. A CMOS threshold voltage extractor circuit creates the conversely proportional to absolute temperature (CTAT) current that decreases with increasing temperature. The reference operates over a temperature range of 0 to 100/spl deg/C with a power supply voltage between 3.3 and 7 V. Simulations show that over these conditions, the output voltage varies by less than 1% over the specified temperature range while using less than 75 /spl mu/A of current.