CML drivers that are built from an open-drain differential pair and a voltage-controlled current source using NMOS transistors.
The outputs (Output+ and Output–) require pullup resistors to VDD because the NMOS transistor can drive only falling edges efficiently and needs the pullups to help drive rising edges.
The output voltage swing is load dependent.
单端P或N: 高电平:VCC 低电平:VCC - 16mA *(50//50)= VCC - 0.4V Note:输出端和输入端50欧姆并联。 差分P-N: 高电平:VCC - (VCC - 0.4V) = 0.4V 低电平:(VCC - 0.4V) - VCC = - 0.4V 摆幅Swing = 0.4 - (-0.4) = 0.8V | |
交流耦合的偏置电压取决于输入端,传过去的只是摆幅 所以,左图只是一个个例! |
The output swing of VML interfaces is independent of the load impedance.