Study Of RFID Reader Rf Front-end Miniaturization Based On LTCC Technology

Radio Frequency Identification(RFID) is a very heated research area in recent years, the hardware of Radio Frequency Identification System mainly composed by two parts, electronic tags and reader. Electronic tags are used to facilitate attachment to the object, its structure is generally simple. In practical applications, passive tag is most widely used, and these kind of technology has been very mature. However, the structure of Radio Frequency Identification reader is much more complicate thanPassive tag. Reader trends to be multi-functional, portable and multi-frequency, to achieve these performance is based on reader miniaturization. The ways to miniaturize reader are mainly miniaturizing antenna and miniaturizing circuit. This paper will research on miniaturizing front end circuit of the RFID reader.Low-temperature co-fired ceramic(LTCC) technology is a new type of microwave integrated circuit processing forms and processes. TR components widely used in high-density RF circuit module. RFID reader dedicated chip makes reader miniaturization a major step forward, while peripheral chip matching circuit occupy a larger area. Here we are going to explore how to use LTCC technology to implement RFID reader front end chip matching circuit, in order to achieve further miniaturization reader circuit.We chose the Austrian microelectronics AS3991 chip as RFID reader RF chip, design and simulate chip peripherals required matching circuit. The matching circuit requires a total capacitance of 22 p F and 6p F two each, 16.3n H and 4n H inductance two each and a total of eight microstrip lines of four models.Next, we are going to design and model the discrete components required for matching circuit. LTCC technology based microstrip line needs hole connection between the matching circuit whole floor on the basis of the original ground plate, so we studied the influence of the number of through-hole on transmission characteristics of microstrip line, and come up with a rational design of microstrip line form. Based on the LTCC technology inductance, we designed a multi-layer embedded within a square spiral inductance. Multi-layer structure reduces the inductance footprint, through theoretical estimation and simulation debugging to determine the size of the inductance. Based on the LTCC technology capacitance, we use hexagonal plates in the form of center-fed, resonant frequency up to 2GHz, reaching the reader work requirements.On the basis of designed discrete components, arrange the LTCC multi-layer layout and wiring of various microstrip lines, capacitance and inductance model. In the layout and wiring, we try to reduce circumstance of transmission lines placed parallel, try increasing the distance between the elements, and take the form of public ground plane symmetrical layout, to design the matching circuit model with 16 layers. Each port reflection coefficient is less than-10 d B, transmission coefficient is greater than-1d B, which meets RFID reader work requirements. In the mean time, compared with matching circuit composed by the tranditional component, miniaturization degree increased by at least 30%.