超宽探地雷达在无损检测系统中应用越来越广泛，采样电路是整个无损系统设计的关键。基于等效采样原理设计出一款新的三极管取样门电路。该电路克服了现有二极管取样门电路的缺点，很好地实现采样保持。利用先进设计系统(ADS)软件对该取样门电路进行仿真，输入脉冲重复频率为 10 MHz的 2 ns三角波信号，采样时钟重复频率为 10 MHz且与被采样信号有 100 ps延时差。对其进行采样，经过该取样门电路后，输出信号为 2 μs。在聚四氟乙烯板上实现该电路，利用信号发生器输入一个 90 ns的正弦波作为被采样信号，采样时钟为 100 ns，经过该取样门电路后，输出信号周期为 1 μs。实测与理论结果都表明该电路可以降低输入信号的频率，实现利用低速 A/D对高速信号的数据采集，大大降低了整个系统的成本。

Ultra-wide ground penetrating radar has been more and more widely used in the non-destructive testing system, and the sampling circuit is the key to the whole non-destructive system design. A new triode sampling gate is proposed based on equivalent sampling principle. The circuit overcomes the shortcomings of the existing diode sampling gate circuit and can well achieve sample-and-hold. Using Advanced Design System(ADS) software to simulate the sampling gate, 2 ns triangular wave with 10 MHz of pulse repetition frequency is input, and a sampling pulse signal with the sampling clock repetition frequency of 10 MHz and a 100 ps delay difference with the sampled signal is utilized. After the sampling gate, the output signal is 2 μs. This circuit is implemented on FR4, and a 90 ns sine wave is input as a signal to be sampled by using a signal generator. The sampling clock is 100 ns, and the signal period after the sampling gate is 1 μs. The measured and theoretical results show that the circuit can reduce the frequency of the input signal, therefore it can use low-speed A/D to acquire high-speed signal, which greatly cut the cost of the entire system.