Considering the low-terahertz transmission power of typical photoconductive antenna (PCA) chips, this study uses Si₃N₄ and silicone gel to passivate and package PCA chips and uses a terahertz time-domain spectroscopy (THz-TDS) system to measure the terahertz waveform. The experiments show that: 1) Si₃N₄ passivation increases the device resistance without laser illumination by approximately an order of magnitude, enhances the terahertz pulse amplitude sixfold, and extends the terahertz spectral width detected in an atmospheric environment from 1.5 THz to approximately 3.0 THz; 2) silicone gel converges or diverges the pump laser beam and improved the dielectric strength of the device at least by 1.4 times, thus enhancing the pulse amplitude by 1.5 times.