Compact Broadband Balanced Filter Based on Integrated Passive Process

In this paper, we propose a compact, broadband balanced filter based on integrated passive process (IPD), which can realize the balanced-unbalanced conversion of microwave signal. The proposed balanced filter is composed of a band-pass filter and a balun, the former selects the working frequency band for the balanced filter, and the latter realizes the conversion of the signal. Simulation results show that the specific operation frequency band of the balanced filter is 2.8 GHz to 4.8 GHz, the insertion loss of the two output ports at the center frequency of 4.37 GHz is −1.514dB and −1.541dB respectively, the phase difference is 180.9°, and the center frequency is within the range of 500 MHz. The insertion loss of the two output ports does not exceed −2.5dB, the maximum difference between the insertion loss of the two ports is about 1 dB, the phase difference fluctuates up and down by ±5°, and the overall size is approximately 1250 $\mu {\mathrm {m}} \times 1250 \mu$m. It has the advantages of compact structure, low loss, frequency bandwidth, low phase deviation, it can be suitable for applications in communication, RF front-end, Bluetooth, WiFi, GPS navigation and other fields.