中文摘要：

在声表面波射频识别系统的实现过程中，性能稳定的阅读器发射链路不可或缺。在典型发射链路结构的基础上进行改进，设计了声表面波阅读器的发射链路。其改进结构采用零中频调制原理，通过射频开关实现了发射信号的调制和收发隔离，省略了上变频电路和环形器，在简化电路的同时减小了干扰。对本振、功放、射频开关等重要的发射链路组成部分进行了研究，完成了发射链路各功能电路的模块化设计与制作，并通过实验对设计要求进行了验证。

英文摘要：

The transmit chain with stable performance is one of the key devices of the radio frequency identifica- tion （RFID） based on SAW. A transmit chain structure of SAW reader has been designed by improving the typical transmit chain structure. The improved structure is based on the principle of zero-IF modulation. The modulation of transmitted signal,the isolation of transmitted and received signals are realized by RF switch. This improved struc- ture excludes the upconverter circuit and the circulator, simplifying the circuit and reducing the interference. The important components of the transmit chain such as local oscillator, power amplifier and RF switch are researched. The design and fabrication of the circuit modules are completed, and the design requirements are verified by experi- ments.