一种转换时间可范围控制的MLVDS驱动器

摘要

In order to realize the high speed data transmission between multi-chips, a Multi-point Low Voltage Differen-tial Signaling(MLVDS)driver for multi-point bus system is presented, which makes the transition-time controlled in a certain range. The main structure of driver consisting of complementary bridge switches can transfer TTL signals to CMOS voltage signals. This structure is proposed to weaken the output waveform distortion caused by substrate bias ef-fect. The pre-drive circuit with constant current charge-discharge circuit structure is used to change the signal slew rate. Meanwhile, by adding two clamping diodes to balance the signals in the output level, signal integrity is ensured. The MLVDS driver is implemented in GSMC 0.18 µm 1P4M CMOS process. The measurement results show that the differen-tial output amplitude is 550 mV and the rising time is 1.190 ns as well as the falling time goes to 1.159 ns when the fre-quency is 125 MHz, which meets the application requirement of the protocol TIA/EIA-899.%为实现多芯片间的高速数据传输，设计了一款应用于多点总线系统的多点低压差分信号（Multi-point Low Voltage Differential Signaling，MLVDS）驱动器，其转换时间可被控制在一定范围内。该驱动器主电路采用互补桥式开关管结构将TTL信号转换成CMOS差分电压信号。这种结构能削弱衬底偏置效应所带来的输出波形失真。预驱动电路采用对电容恒流充放电电路结构改变信号的压摆率。在输出级通过添加两个泄流二极管来平衡信号的过冲，从而保证了信号的完整性。芯片采用GSMC 0.18µm1P4M的CMOS工艺实现，测试结果表明工作频率为125 MHz时输出信号幅值为550 mV，上升时间为1.190 ns，下降时间为1.159 ns，满足TIA/EIA-899协议的要求。