Development of high-speed LiNb3 optical switch with CMOS driver circuit

“光开关”是光信号在不需要电光转换的情况下改变传输路径的关键器件。在高速光通信中，使用LiNbO_3和半导体器件的外部光开关已经投入实际使用。对于小型网络，即路由器，而不是主干网，实现更高速率和更低功率的光交换的需求仍然很大。从驱动器电路施加的调制电压必须传输到开放式传输线。为了实现高速光交换，设计了与开放式传输线相连的高速低功耗驱动电路，为了实现低功耗，采用了以CMOS型反相器结构为核心的低功耗驱动电路，从而得到了备用的低功耗驱动电路。为了得到我们的LiNbO_3光开关的开关电压，我们将NMOS和PMOS场效应管堆叠在一起，反相器的传输延迟依赖于…更多的是S对负载电容(C_L)和输出电阻(R_&lt；OUT&gt；)的讨论，其中C_&lt；OUT&gt；主要是该电路上MOS的寄生电容。C_&lt；out&gt；和R_&lt；out&gt；应该是较小的值，以抑制传播延迟。然而，当增加栅宽以获得较小的R_&lt；out&gt；值时，C_&lt；out&gt；增大。为了解决这个问题，我们通过在驱动器电路的输出端插入集总电感(L)来补偿C&lt；OUT&gt；。然而，在CMOS工艺中，由于高频段的自谐振和杂散阻抗，利用螺旋电感制作大电感是很困难的。因此，我们提出了一种新的方法，通过将栅宽划分为n级来减小Cout和栅电容，并在划分的漏极线和栅极线的输出端和输入端之间插入具有高特性阻抗的传输线来补偿每个电容。分布式驱动器从10%到90%V_OUT&>的切换时间为0.0315纳秒，比以前的版本快31.5%。较少

"Optical switch" is the key device, which changes the route of optical signal without electro-optic conversion. In the high-speed optical communications, external optical switches using a LiNbO_3 and semiconductor devices have already been operated for practical use. There have still been great needs for realizing higher-speed and lower power optical switch for small networks, i.e., router, rather than main networks. The modulation voltage applied from the driver circuit must be transmitted to the open-ended transmission line. In this resarch, we designed the high speed and low-power driver circuit connected to the open-end transmission line for realizing high-speed optical switch.For realizing the low power dissipation, we adopted the CMOS inverter structure as a core circuit, so that, we obtain the stand-by power less driver circuit. In order to obtain the switching voltage of our LiNbO_3 optical switch, we stacked each nMOS and pMOS FET.The propagation delay of CMOS inverters depend … More s on the load capacitance (C_L) and the output resistance (R_<out>), where C_<out> mainly consists of parasitic capacitance of MOS on this circuit. C_<out> and R_<out> should be small values to suppress the propagation delay. However, when the gate width is increased in order to obtain the small value of R_<out>, C_<out> increases. To solve this problem, we compensated for C_<out> by inserting lumped inductance (L) in the output of the driver circuit. However, in the CMOS process, it is difficult to fabricate large inductance by spiral inductor because of the self-resonance and stray impedances in high frequency range. So, we propose a new method, which decrease C_<out> and gate capacitance by dividing gates width into n stage and compensate each capacitances by inserting transmission lines with high characteristic impedance between the output and input point of the divided drain line and gate line. Switching time from 10% to 90% V_<out> of the distributed type driver is 0.0315 nsec which is 31.5% faster than that of previous version. Less