一种低功耗、高增益的精密运算放大器设计OA

A four-channel precision operational amplifier with low power consumption and high gain is designed based on the 40 V bipolar process to ensure high-precision performance such as low input offset voltage and low input bias current,while achieving low power consumption and high gain.The bias circuit can generate a stable current insensitive to supply voltage and temperature variations by combining the CTAT derived from base-emitter voltage(VBE)with the PTAT current source.The high-precision base current compensation structure is designed for the fully differential input stage to achieve low input bias current.In the gain stage,a folded cascode structure is used to enhance the circuit gain.In the output stage,the double-buffered structure is used to isolate the high-impedance influence of the preceding stage and improve the load-carrying capacity of the circuit.In the overall circuit,the Miller compensation is used to improve system stability without the need for zero-adjustment resistors,and zero-pole distribution can be realized by means of precise current regulation.The actual measurement results of the chip show that,within the full temperature range,under the condition of a 15 V dual power supply,the input offset voltage is 21.75 μV,the input offset current is 0.194 5 nA,the input bias current is 0.359 nA,the open-loop voltage gain at a resistive load of 10 kΩ is 136.941 5 dB,and the supply current of a single operational amplifier is 0.675 mA.The designed circuit can be applied to precision measurement systems,sensor signal conditioning,high-precision active filters,and other fields.