| Low Voltage Differential Signal(LVDS)is widely used for data transmission due to its fast transmission speed and low power consumption.However,the electronic components of integrated circuits in the space environment are inevitably exposed to radiation effects such as single event effect radiation and total ionizing dose radiation,which can lead to reduced stability and even malfunction of electronic components,resulting in reduced speed and increased power consumption of LVDS interface circuits.Therefore,it is essential to enhance the stability of LVDS circuits by reinforcing them against radiation.To reduce the negative effects of radiation on the LVDS interface circuit,this paper designs a radiation hardened LVDS interface circuit based on a 65 nm 1P5M CMOS process,which mainly includes an LVDS driver and an LVDS receiver and carries out radiation hardened reinforcement in the circuit and layout.The main contributions of this thesis are as follows:1.In the LVDS driver design,a H bridge type structure is used to output±350 m V differential signal stably at 100Ωload from the single-ended CMOS signal.To provide a stable voltage to the driver core module,a self-biased structured bandgap reference circuit is designed that can operate from-55°C to 125°C.In order to convert single-ended signal to double-ended signals,a driver core module inverter chain circuit is designed to determine the optimum number of stages to ensure the lowest transmission delay of 5 stages,a common mode feedback circuit to improve circuit stability,and a switching transistor circuit to output signals.To improve the irradiation resistance of the LVDS driver,a single event pulse simulation is performed on 26 nodes,four nodes in the bandgap reference are identified as sensitive nodes and three-mode redundant reinforcement is used for the radiation hardened design.2.In the LVDS receiver design,a hysteresis comparator is used to suppress common mode and differential mode noise in the circuit and a threshold jump voltage is reasonably designed to improve circuit stability.A buffering and shaping circuit is designed to adjust the output signal waveform and a parallel fail-safe circuit is added to keep the receiver at high level all the time,protecting the circuit without influencing the normal operation of the receiver.The receiver successfully converts the double-ended CMOS signal coming from the driver to a single-ended signal.3.In the layout design,to improve the circuit stability under the total ionizing dose effect radiation environment,three radiation hardened layout techniques of annular ring,strip ring,inverse proportional and small proportional NMOS tubes are used to solve the impact of parasitic capacitance at the edge of NMOS devices and reduce leakage current.Diodes and GGNMOS devices are also added for ESD protection between the power supply and ground,between the interface and the next level input,and between the driver single-ended to double-ended circuit output interface and the power supply and ground.The designed LVDS interface circuit in this thesis is finally simulated and verified by flowing the chip.The transmission speed is 200 Mbps at 3.3 V operating voltage,the driver layout area is 464.715×351.985μm~2 and the receiver layout area is 535.22×441.6μm~2.The radiation experiments use Ge particles as the radiation source,with particle energy of 210 Me V,range of 30.5μm in silicon,linear energy transfer LET of 37.3 Me V·cm~2/mg,average injection rate of 8000 n/(cm~2·s)and total incident injection of 10~7 n/cm~2.During the experiment,the test system does not record any error in the LVDS transmission data. |
