Research And Design Of Instrument Amplifier Circuit For High Speed Current Sensor

With the development of science and technology,electric energy became an indispensable part of human life after the electrical industrial revolution,that providing an energy for people's production and life.Based on the safety problem of electric power,the current detection has gradually become a important thing.Traditional current detection devices such as shunts,transformers,Rogowski coils and so on have their own drawbacks.Such as accuracy reasons,volume reasons,and some of those devices need contact with the circuit,it is difficult to work in complex environments.So that various current sensors came into being,and are widely used in the automotive industry,control engineering,power management and other fields.The rapid development of the Internet of Things puts higher demands on the speed of current sensors.The research and design of instrumentation amplifiers in this thesis mainly includes the following two parts:(1)Aiming at the problem of small bandwidth of traditional instrumentation amplifiers,a high-bandwidth,large-swing amplifier unit is designed as a component to construct a three-op-amp instrumentation amplifier,So that the instrument amplifier can obtain a lager bandwidth.The amplifier unit uses the Ping-Pong auto zeroing technology to reduce the offset,the two stage Class AB amplifier is added to traditional Ping-Pong structure,that improve the output swing and gain of the amplifier.That gives it a large bandwidth and fast large signal response speed while reducing the offset voltage.(2)Aiming at the problem of the traditional auxiliary amplifier auto zeroing loop limit the common mode voltage of main amplifier,a auto zeroing loops were designed.The problem that the common mode voltage of the main amplifier is limited by the auto zeroing loop is solved,and use that to solve the problem of offset,Different from chopper technology,use auto zeroing technology to compensated offset does not limit bandwidth.The disadvantage is that its performance is lower than that of chopper technology.The design is based on SMIC 0.18?m CMOS technology,the supply voltage is 5V.This thesis use Cadence to complete circuit design,simulation verification,layout design and parasitic parameter extraction.The chip area is 1.59mm X 1.46mm,input reference noise is 2.8nV,input reference offset voltage of 400uV,the power consumption is 4.5mA,and the-3dB bandwidth is up to 965kHz,which basically meets the requirements of the current sensor readout circuit.This circuit is verified by simulation,and the tape-out is completed.Then measured some of the performance parameters of the chip,the circuit measured input reference offset voltage maximum is 280 ?V,signal slew rate is 15V/?s,the-3dB bandwidth is 950kHz.