|dc.description.abstract||In this study, highly integrated RF frontend designs are presented. First, the novel bandpass single-pole-double-throw (SPDT) RF switch design that combines the functions of bandpass filter (BPF) and SPDT is proposed. As a result, both the circuit size and mismatch losses associated with the cascade of these two components in the RF frontend of conventional time-division-duplex system can be reduced. The proposed SPDT BPF design starts from a microstrip parallel-coupled BPF loaded with a p-i-n diode at the end of first coupled-line. In this way, the BPF becomes switchable. By properly chosen the length of first coupled-line, two switchable BPFs can be directly connected to form a SPDT BPF. In addition, since only the first coupled-line is determined by the switch function, the subsequent filter stages can be arbitrarily designed such them more functions can be integrated and more design freedom is obtained. For instance, the integration of balun function to the bandpass SPDT switch is demonstrated, such that the level of integration is further improved. Moreover, the design technique of BPF with complex load is applied to the matching network design of a Low Noise Amplifier (LNA). In this way, a SPDT switch, two BPF’s, and a LNA are all integrated in a single circuit. It will help reducing the circuit size, mismatch losses, and complexity in module for RF frontend design.
The proposed SPDT BPF features compact circuit structure and simple design flow, and is capable of further integration of other circuit components. The integration of several active and passive function blocks in the RF frontend has been achieved. The proposed circuit structure and design method also paves the way for further improvement in the near future.