一款用于Flash型FPGA的阶梯式配置方法

A step configuration method for Flash-based FPGA

为了提高Flash型FPGA中的Flash开关单元在擦除、编程后驱动能力的一致性,设计一种阶梯式的对Flash cell进行擦除和编程的方法.通过该方法依次对Flash开关单元执行若干次配置操作,执行完一次配置操作后通过Flash电流读出电路回读Flash开关单元的电流,并基于回读的电流调整下一次配置操作的参数,直至完成配置操作;该阶梯式控制的编程和擦除算法,及时调整编程和擦除时的操作电压和时间参数,可以实现对Flash开关单元在擦除和编程后阈值电压分布的精确控制,保证了驱动的一致性,为Flash型FPGA提供了高精度的延迟参数.并且采用阶梯式的配置方法很好的控制了Flash cell过擦除和过编程现象的发生,使电流读取电路能够对Flash cell的电流进行准确的读取.实测结果表明使用该阶梯式的配置方法可以将擦除、编程后的Flash cell阈值电压控制在预设范围之内.

In order to improve the consistency of Flash switch cell in Flash based FPGA after erasing and programming,a step method of erasing and programming Flash cell was designed.This method is used to perform several configuration operations on the Flash switch cell successively.After one configuration operation,the Flash current reading circuit reads back the Flash switch cell current,and adjusts the parameters of the next configuration operation based on the current reading back until the configuration operation is complete.By adjusting the operating voltage and time parameters during programming and erasure,the step control algorithm can accurately control the threshold voltage distribution of Flash switch cell after erasure and programming,ensuring the consistency of driver,and providing high precision delay parameters for Flash based FPGA.And the step configuration method is used to control the occurrence of Flash cell over-erasing and over-programming,so that the current reading circuit can accurately read the current of the Flash cell.The experimental results show that the threshold voltage of the erased and programmed Flash cell can be controlled within a preset range by using this step configuration method.