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硅基功率MOSFET产品已经十分成熟,选择国产某型号MOSFET作为激光器驱动芯片功率管芯,该管芯具有开关延时小,导通电阻低,输出电流大,面积小(约2 mm×2.3 mm)等优势;国内现有栅极驱动管芯存在面积大,性能较差等问题,所以有必要设计一款专用栅极驱动管芯与功率MOSFET管芯匹配,文中提出了设计方案,此方案在减小多芯片封装的寄生效应和增加封装可靠性方面进行了优化。
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激光探测系统性能很大程度上取决于光脉冲质量,因此驱动芯片需要提供上升时间短、脉冲宽度窄的大电流脉冲信号[7]。表1给出了该栅极芯片的设计指标。在输出脉冲频率为10 kHz时,系统能有效且快速地探测到目标[8]。
表 1 栅极驱动芯片设计指标
Table 1. Design index of gate driving chip
Frequency/kHz Pulse width/ns Rising and falling edge/ns Index 10 ≤200 ≤20 该栅极驱动管芯主要包括输入级、逻辑电路、输出级、低压线性稳压器(LDO)以及欠压保护五个模块,原理框图如图3所示。输入信号经过输入接口模块得到低压方波信号,该信号输入到逻辑控制模块,逻辑控制模块将其与欠压保护、启动保护等信号综合后,把得到的信号输出到驱动模块,由驱动模块产生驱动信号。
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输入级接口电路使用施密特触发器,如图4所示,利用滞回效应提高系统抗噪和抗干扰能力。
输出脉冲宽度为:
$$ t=R\times C\times \ln\frac{{V}_{CC}}{{V}_{CC}-{V}_{T+}} $$ (1) $$ {V}_{T+}=\dfrac{{V}_{CC}+\sqrt{\dfrac{{\beta }_{3}}{{\beta }_{5}}}\times {V}_{TH}}{1+\sqrt{\dfrac{{\beta }_{3}}{{\beta }_{5}}}} $$ (2) 式中:
$ {\;\beta }_{3},\;{\;\beta }_{5} $ 为MN3,MN5的宽长比。 -
为了节省版图面积,该电路使用MP2-MP6,MN5-MN8管构成折叠共源共栅放大器,如图5所示,在电源与开关管MP7栅极之间串联RC,简化补偿网络。
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由于PMOS的沟道迁移率远低于NMOS,在提供相同电流输出时,PMOS元件所占版图面积很大。该电路在输出级增加了NMOS上拉结构,如图6所示,将N沟道MOSFET与P沟道MOSEFT并联,减小了管芯版图面积的同时,增加了输出驱动电流。
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该栅极驱动管芯版图设计对寄生效应和过流能力方面进行了优化。
输出级版图位于整体版图右侧,缩短输出焊盘与MOSFET栅极之间的距离以减小寄生效应;增加栅极驱动输出焊盘尺寸,焊盘开窗100 μm×100 μm焊盘,以增强过流能力,提高多芯片的稳定性。栅极驱动管芯整体版图如图7所示,版图面积为1.7 mm×2 mm。该管芯采用0.25 μm BCD工艺加工制作。
Design of high current narrow pulse laser driving chip
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摘要: 脉冲式半导体激光器的出光质量直接影响探测精度。针对激光探测系统小型化的需求,设计一款面积小、集成度高的激光器驱动芯片。该芯片使用新型3D堆叠式封装技术将栅极驱动管芯与功率场效应晶体管管芯集成,并在中间添加双面覆铜陶瓷基板实现两管芯互连。该封装形式既提高了芯片的散热能力,又增强了过流能力。首先对激光探测发射模块现状进行详细介绍,引出了激光器驱动芯片的设计思路与方法,并给出了具体的封装设计流程。对栅极驱动电路与版图进行设计,使用0.25 μm BCD工艺制造栅极驱动芯片。在完成激光器驱动芯片封装后,搭建外围电路进行测试,使该芯片驱动860 nm激光器,芯片供电电压为12 V时,输入电平为3.3 V、频率为10 kHz的PWM信号,芯片输出脉冲宽度为180 ns的窄脉冲,其上升、下降时间小于30 ns,峰值电流高达15 A,可以使激光器正常出光,满足探测需求。芯片具有超小面积,约为5 mm×5 mm,解决了传统激光器驱动电路采用多芯片模块造成探测系统内部空间拥挤的问题,为小型化提供新思路。Abstract: The light quality of the pulsed semiconductor laser directly affects the detection accuracy. Aiming at the miniaturization requirement of laser detection system, a laser driving chip with small area and high integration was designed. The chip integrated the gate driving die and the power field effect transistor die using 3D stacked packaging technology, and added a double-side copper-clad ceramic substrate in the middle to realize the interconnection of the two dies. This packaging form not only improved the heat dissipation capability of the chip, but also enhanced the overcurrent capability. First, the current status of the laser detection transmitter module was introduced in detail, the design ideas and methods of the laser driver chip were introduced, and the specific packaging design process was given. Then, the gate driving circuit and layout were designed, and the gate driving chip was fabricated with a 0.25 μm BCD process. The multi-chip packaging scheme was designed. By setting up a peripheral circuit for testing to make the chip drive the 860 nm laser, the chip can output a narrow pulse with a pulse width of 180 ns, rise and fall times were less than 30 ns, and reached a peak current as high as 15 A when the chip power supply voltage was 12 V, the input level was 3.3 V and the frequency is 10 kHz PWM signal. It can make the laser emit light normally and meet the detection requirement. The chip has an ultra-small area about 5 mm×5 mm, which solves the problem of congestion in the internal space of the detection system caused by the traditional laser drive circuit using multi-chip modules, and provides a new idea for miniaturization.
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Key words:
- semiconductor laser /
- driving chip /
- miniaturization /
- 3D packaging /
- power MOSFET
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表 1 栅极驱动芯片设计指标
Table 1. Design index of gate driving chip
Frequency/kHz Pulse width/ns Rising and falling edge/ns Index 10 ≤200 ≤20 -
[1] Gao Yejun. Analysis of the research status and development process of fuze system in foreign countries [J]. Guidance and Fuze, 2018, 39(1): 1-5. (in Chinese) [2] Wang Jinhua, Chen Feixia. Design of realizing laser fuze circuits system miniaturization with CPLD [J]. Infrared and Laser Engineering, 2000, 29(4): 67-70. (in Chinese) [3] Han Wei, Zheng Xiang, Zhao Baiqin. Design of miniaturized transmitting-receiving system for laser detection [J]. Infrared and Laser Engineering, 2017, 46(9): 0906008. (in Chinese) [4] Chen Shanshan, Zhang He, Xu Xiaobin. Design of narrow pulse light source driving circuit of laser fuze [J]. Infrared and Laser Engineering, 2018, 47(S1): S106004. [5] Yang Jiansheng. Development of three-dimensional memory die stack packages technique [J]. Equipment for Electronic Products Manufacturing, 2018, 47(47): 40-44. (in Chinese) [6] Tong Zhiyi. The present situation of high-density packaging and its future [J]. Equipment for Electronic Products Manu-facturing, 2000, 29(2): 1-9. (in Chinese) [7] Cong Menglong, Li Li, Cui Yansong, et al. Design of high stability digital control driving system for semiconductor laser [J]. Optics and Precision Engineering, 2010, 18(7): 1629-1636. (in Chinese) [8] Dai Qin, Song Wenwu, Wang Xijun. Design and stability of high frequency LDs driving circuit [J]. Optics and Precision Engineering, 2006, 14(5): 745-748. (in Chinese)