Absorption filter

Abstract

The utility model discloses an absorption type filter, which comprises an electric bridge, two reflection type filters and two loads, the electric bridge, the reflection type filters and the loads are all connected in series in a circuit, the electric bridge comprises two 90-degree electric bridges, the number of the reflection type filters is two, and the number of the loads is two. According to the utility model, the absorption type filter adopts a double-branch structure and is respectively composed of two 90-degree bridges and two reflection type filters, reflection wave signals at the input end and the output end of the two reflection type filters are acted by the 90-degree bridges to generate two paths of reflection wave signals with equal amplitude and reverse directions, and the signals are synthesized and absorbed by the absorption load of the 90-degree bridges.

Description

Technical Field

[0001] The utility model relates to the technical field of filters, in particular to an absorption filter. Background Art

[0002] Absorption filters are mainly used in RF circuits, PLLs, oscillation circuits, and ultra-high frequency memory circuits (DDRSDRAM, RAMBUS, etc.). Their main function is to convert interference signals, especially electromagnetic energy of high-frequency interference signals, into heat energy, consume it, and thus achieve filtering effects. When used, the current filter has a reflection characteristic outside the port band, and cannot be well matched with the mixer cascade, resulting in load pulling, which leads to large amplitude fluctuations within the band.

[0003] In view of the above problems, the utility model provides an absorption filter with small amplitude fluctuation within the band. Utility Model Content

[0004] The utility model provides an absorption filter with small amplitude fluctuation within the band.

[0005] The utility model aims to provide an absorption filter, comprising a bridge, a reflective filter and a load, wherein the bridge, the reflective filter and the absorption load are all connected in series in a circuit, the bridge comprises two 90° bridges, the number of the reflective filters is two, and the number of the absorption loads is two.

[0006] Furthermore, the reflective filter includes a resonant capacitor, a resonant inductor and a coupling capacitor. The resonant capacitor and the resonant inductor are connected in parallel to form a resonant cavity, which is then connected in series with the coupling capacitor.

[0007] The utility model has the following advantages: the utility model adopts a dual-branch architecture through an absorption filter, which is composed of two 90° bridges and two reflective filters respectively. The reflected wave signals at the input and output ends of the two reflective filters are acted upon by the 90° bridge to generate two equal-amplitude, reverse reflected wave signals, which are synthesized and absorbed by the absorption load of the 90° bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a principle block diagram of the utility model;

[0009] Figure 2 It is the circuit principle diagram of the utility model;

[0010] Figure 3 It is a phase relationship diagram of signals within the passband of the utility model;

[0011] Figure 4 It is the phase relationship diagram of the out-of-channel signal of the utility model;

[0012] Figure 5 It is a simulation curve diagram of the utility model. DETAILED DESCRIPTION

[0013] The utility model provides an absorption filter, comprising a bridge, a reflection filter and a load. The bridge, the reflection filter and the absorption load are all connected in series in a circuit. The bridge comprises two 90° bridges, the number of the reflection filters is two, and the number of the absorption loads is two.

[0014] In this embodiment, the reflective filter includes a resonant capacitor, a resonant inductor and a coupling capacitor. The resonant capacitor and the resonant inductor are connected in parallel to form a resonant cavity, which is then connected in series with the coupling capacitor.

[0015] In this embodiment, a dual-branch architecture is adopted, which is composed of two 90° bridges and two reflective filters. The reflected wave signals at the input and output ends of the two reflective filters are acted upon by the 90° bridge to generate two equal-amplitude, reverse reflected wave signals, which are synthesized and absorbed by the absorption load of the 90° bridge.

[0016] In this embodiment, the signal within the passband is subjected to the action of a 90° bridge to generate two signals of equal amplitude and a phase difference of 90°. After passing through two completely identical reflective filters, the phase is kept unchanged. Then, the two signals of equal amplitude and in-phase are synthesized (signals with a phase difference of 0°) by the action of a 90° bridge.

[0017] In this embodiment, the out-of-band signal is subjected to the action of a 90° bridge to generate two signals of equal amplitude and a phase difference of 90°. After being reflected by two identical reflective filters, the phase is kept unchanged. The two signals of equal amplitude and anti-phase (signals with a phase difference of 180°) are then synthesized through the action of a 90° bridge, and the canceling signal is absorbed by the absorption load.

[0018] In this embodiment, the return loss of the absorptive filter in the stop band of 4 GHz to 8 GHz can be greater than 10 dB.

[0019] Although the specific implementation of the utility model is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. An absorptive filter, comprising a bridge, a reflective filter and a load, characterized in that: The bridge, reflective filter and absorption load are all connected in series in the circuit, the bridge includes two 90° bridges, the number of the reflective filters is two, and the number of the absorption loads is two; the reflective filter includes a resonant capacitor, a resonant inductor and a coupling capacitor, the resonant capacitor and the resonant inductor are connected in parallel to form a resonant cavity, and then connected in series with the coupling capacitor.

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