A radio frequency interface circuit

Abstract

The invention discloses a radio frequency interface circuit, which includes a PCB board. On the top layer of the PCB board, from one end to the other end, there are sequentially provided a first pad, a second pad and a transmission line. The first pad plate and the second pad are respectively used for dragging the shielding ground net and the core wire of the tin welding shielded cable; the first impedance matching network for compensating the impedance is also provided on the PCB board, and the first impedance matching network includes matching stubs and Metallized vias, the matching stubs are set on the bottom of the PCB, and a second hollow area is set around the matching stubs, the metallized vias are set in the PCB board, and the two ends of the metallized vias are respectively connected to the second pad and the matching stubs . The invention can eliminate the inherent impedance discontinuity of the original radio frequency interface circuit and the difference of different frequency bands, reduce the high-frequency standing wave ratio and insertion loss, thereby realizing ultra-wideband impedance matching.

Description

technical field [0001] The invention relates to the technical field of circuit board design, in particular to a radio frequency interface circuit. Background technique [0002] With the gradual application of WiFi 6 and 5G technology, the frequency of radio frequency (RF) is getting higher and higher, and the RF interface circuit or antenna connector used to connect the antenna to the PCB (Printed Circuit Board, printed circuit board) is extended to Frequency bands above 5 GHz present significant challenges. IPEX (Interconnect and Packaging Electronics, electronic assembly interconnection) antenna connector is used as the interface between the radio frequency interface circuit and the antenna. Due to its small size and low price, it is widely used in WLAN (Wireless Local Area Network, wireless local area network), routers, GPS, mobile phones and other products on the board for radio frequency signal transmission. [0003] see figure 1 with figure 2 As shown, the most co...

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Problems solved by technology

[0003] see figure 1 and figure 2 As shown, the most commonly used PCB processing method for the IPEX antenna connector 9 on a single board at present is: two third pads 8 and one second pad 3 are provided on the PCB 1, and the third pad 8 and the second pad The pads 3 are respectively used for mounting and welding the ground pad and the antenna pad of the IPEX antenna connector 9, and the second pad 3 is directly connected to a pin 41 of the DC blocking capacitor through a 50ohm transmission line (usually a microstrip transmission line) 4 ( figure 1 The pad on the right side of pin 41 is another pin of the DC blocking capacitor), simulation and actual tests show that this conventional PCB processing method has some disadvantages: as the operating frequency increases, the VSWR of IPEX antenna connector 9 (Voltage Standing Wave Ratio, standing wave ratio) is on the rise, and the insertion loss will also increase accordingly, especially the problem of large standing wave ratio and large loss in the frequency band above 5GHz, so the transmission of high-frequency signals above 5GHz is harmful to the RF interface circuit. Or the insertion loss and impedance matching of the antenna connector put forward stricter requirements

The standard RF interface circuit form of traditional PCB is difficult to meet the different welding methods of mounting and drag welding

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