Design And Fabrication Of Flexible RF Circuits On Plastic Substrates

Flexible electronics with stretchable bending characteristics have been widely used in emerging fields such as wearable,health detection and digital medical under the context of the popularity of flexible electronic devices in various areas in recent years.It is for the huge market potential and application value of flexible electronic,many materials have been studied and used in the field of flexible stretchable.At present,there have been many advances in the field of high-speed flexible electronics at home and abroad,but most of the research results focus on the design and manufacturing of high-speed devices,but design and performance studies for flexible radio frequency circuits are still very limited.In this paper,a flexible low-noise amplifier and a flexible single-ended mixers with an operating frequency of 433 MHz are designed as an example of the core low-noise amplifier and mixer in radio frequency communication systems,and the effects of non-ideal characteristics of flexible devices and different bending radii on circuit performance are characterized and analyzed.The main task and innovation of this paper are as follows: the flexible spiral inductor and MIM capacitor are modeled and analyzed based on the single crystal silicon thin film transistor on flexible substrate and compatible with its substrate process using simulation software ADS and HFSS,and the accuracy and reliability of the model are verified by comparing the actual measurement data with the model data.The operating frequency selection is carried out by combining the operating performance of flexible monocrystalline silicon thin-film transistors with the application scenarios of flexible circuits,and the operating frequency centered on 433 MHz was determined.Then the stability and input-output matching network design of the circuit is carried out by relying on the flexible device model established in this paper,and it is optimized and adjusted to realize a flexible low-noise amplifier with a gain of17.8 d B and a noise figure of 3.502 d B.In addition,the DC operating point selection and input-output impedance matching of the flexible mixer are carried out,and a flexible active single-ended mixers with radio frequency input of 433 MHz,LO of 333 MHz,and IF output of 100 MHz was designed with a 1 d B compression point of 1 d Bm,frequency conversion gain of 6.332 d B,and noise figure of 10.933 d B.The variation of the circuit operating performance on a flexible substrate compared to an ideal rigid device is analytically characterized,and the effect of the non-ideal characteristics of the flexible device under flat conditions,especially the equivalent series resistance of the flexible inductor,on the circuit performance is investigated.The changes in circuit performance at different bending radii are also compared,and the analysis concludes that the flexible capacitance-inductance value,which varies with the bending radius,is the main factor affecting the circuit performance.This paper provides guidance for the design of flexible circuits at higher frequencies and more complex structures,and lays the foundation for the application of flexible devices in radio frequency circuits.