A GaAs Integrated Power Divider Based on Microstrip and LC Structure with Optimized Capacitance

Abstract

In this paper, a microstrip LC two-section Wilkinson power divider based on GaAs IPD process is proposed. A method on adjusting circuit parameters is demonstrated, which can compensate the parasitic effects of frequency-dependent passive components. One of the sections is a lumped LC network and the other section consists of microstrip lines. This design can reduce the size of the power divider and avoid a high loss. The inductance and capacitance of this power divider are calculated to ensure that the LC network is equivalent to a microstrip line. However, the capacitances and inductances are all sensitive to frequency so there is a significant variation among calculation with ideal components and simulation with practical models. To solve this problem, even-mode input admittance is studied. By plotting a polar diagram of ideal and simulated even-mode input admittances, it is clear that a difference exists among simulation and ideal target, which causes the performance degeneration. This polar diagram also indicates a method on optimizing the admittance by increasing capacitance in the LC network. Increased capacitances are utilized in power divider simulation. Simulated results are compared and an optimized capacitance, which guides our final design, is obtained. This power divider is fabricated using GaAs IPD process and measured on wafer. Measurement agrees well with simulation: operation band is 2.850 GHz to 4.832 GHz. A 1.982 GHz bandwidth is achieved. The insertion loss of port 2, 3 is less than 1.30 dB in this frequency range, and the isolation is higher than 18.5 dB.