Broadband and Low Loss Directional Coupler Based on GaAs-IPD Technology for C-Band Application

In this paper, a directional coupler is achieved through first-order and second-order circuit structures based on GaAs integrated passive manufacturing process. Based on the circuit structure of the proposed novel symmetric topology, different topologies and corresponding transmission characteristics can be obtained by using the odd-even mode analysis on it. The first-order directional coupler operates from 0.4 GHz to 1.4 GHz, with insertion loss <0.5 dB, return loss > −15 dB, coupling < −20 dB, isolation < −50 dB, and the size is 1.4 mm $\times 1.3$ mm $\times 0.2$ mm. The second-order directional coupler operates from 3 GHz to 8 GHz, insertion loss < 0.5 dB, return loss > −20 dB, coupling <−20 dB, isolation > −60 dB, the size is 1.5 mm $\times 1.3$ mm $\times 0.2$ mm. This work realizes quantitative power distribution and measurement and monitoring of desired signals in a wide frequency band with low loss, which can improve the integration of microwave integrated circuits.