LTCC-based L-waveband miniature quadrature filter

The invention brings forward an LTCC-based L-waveband miniature quadrature filter comprising an L-waveband filter and a directional coupler. In the filter, an input port, an output port, a first ground terminal, and a second ground terminal are ports with surface mounting structures. A resonance unit at each stage is formed by three layers of strip lines arranged in parallel; one end of the first strip line layer of the resonance unit and one end of the third strip line layer of the resonance unit are connected with the first ground terminal and the other ends are in an open circuit mode; and one end of the second strip line layer of the resonance unit is connected with the second ground terminal and the other end is in an open circuit mode. One end of an input lead is connected with the open-circuit end of the second strip line layer of the first-stage resonance unit and the other end is connected with the input port; one end of an output lead is connected with open-circuit end of the second strip line layer of the fourth-stage resonance unit and the other end is connected with the output port. According to the invention, the optimum performance can be realized in a minimized size; and specific-frequency screening of one path of signals can be realized and two paths of orthogonal signals are outputted.