Design of an outer-chip controllable and inner-chip adjustable voltage reference

A new type of voltage reference which can be controlled in the outer-chip by the external pins and can generate an arbitrary reference voltage was introduced in this paper. There is a resistor serial in the reference voltage circuit that can generate 4 different reference voltages by the internal control logic circuit to adapt to fit different situations demand. The core circuit employs the improved Brokaw architecture. The entire circuit is in 0.18um CMOS process and the power supply voltage is 1.8V. Simulation results using Hspice tools show that different reference voltages can be achieved by corresponding configurations of external pins; or can output 4 fixed reference voltages controlled by the internal logic signals. When the temperature ranges from −40 to 120°C, the reference voltage circuit can reach to a low temperature coefficient (8.5ppm/°C) and a high power supply rejection ratio that is −110.2dB.1