摘要
导波雷达物位计是一种利用时域反射(TDR)原理实现的高性能物位计,因其测量精确,性能稳定,在现代工业的多个领域得到了广泛地应用。雷达物位计一般采用窄脉冲发射—反射—接收的工作方式进行物位测量,可见脉冲发射电路是其中至关重要的一环。论文在分析和比较常用的几种极窄脉冲产生电路的基础上,提出了采用射频三极管串行级联、并行触发的发射电路设计方案。这样设计不仅可以使三极管在较低偏置电压下雪崩导通,还能有效地消除雪崩依次时延和减小输出脉冲的上升时间。测试结果显示该发射电路能够产生脉宽901.9ps,幅值2.25V的极窄脉冲,满足了导波雷达物位计对发射脉冲的要求。
Guided wave radar level meter is a high performance level meter which makes use of the time domain reflectometry principle.Its measurement accuracy and stable performance has made it be widely used in many areas of modern industry.Radar level meter generally take the way of a narrow pulse emission—reflection—reception for level measurement,so pulse transmitter circuit is one of the vital part.Based on the analysis and comparison of several commonly used very narrow pulse generating circuit,this paper puts forward the transmitter design of RF transistor serial cascade and parallel triggering.This design not only makes the transistor avalanche conduction at a lower bias voltage,and can effectively eliminate avalanche latency in turn and reduce rise time of output pulse.Measured result shows that the transmitter circuit can generate a narrow pulse with 901.9ps pulse duration and 2.25Vamplitude which meets the requirement of guided wave radar level.
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