A Fully CMOS Low Voltage Bandgap Reference without Resistors

A new method to generate a reference voltage is introduced. A fraction of the forward voltage of a pn-junction implemented by a PMOS transistor with negative temperaturecoefficient (TC) is combined with a voltage produced by a CMOS floating proportional to absolute temperature (PTAT)voltage source. The combined output voltage will be a referencevoltage with minimum variation with temperature while no resistance has been used in the circuit. The circuit is designedand simulated in a 0.18 μm CMOS technology which simulation results show the circuit is able to generate an output voltage of695.6 mV with TC of 18 ppm/℃ in the temperature range of -20 ℃ to +120 ℃. Monte Carlo analysis considering both mismatchand process variations gives σ⁄μ=1.08%. The total power consumption of the circuit is about 8.9 μW at the supply voltage of 1.5V.