Design and fabrication of a series contact RF MEMS switch with a novel top electrode

Radio-frequency(RF)micro-electro-mechanical-system(MEMS)switches are widely used in communication devices and test instruments.In this paper,we demonstrate the structural design and optimization of a novel RF MEMS switch with a straight top electrode.The insertion loss,isolation,actuator voltage,and stress distribution of the switch are optimized and explored simultaneously by HFSS and COMSOL software,taking into account both its RF and mechanical properties.Based on the optimized results,a switch was fabricated by a micromachining process compatible with conventional IC processes.The RF performance in the DC to 18 GHz range was measured with a vector network analyzer,showing isolation of more than 21.28 dB over the entire operating frequency range.Moreover,the required actuation voltage was about 9.9 V,and the switching time was approximately 33μs.A maximum lifetime of 109 switching cycles was obtained.Additionally,the dimension of the sample is 1.8 mm×1.8 mm×0.3 mm,which might find application in the current stage.

一种L~U波段RF MEMS单刀十掷开关的设计

论文提出了一种适用于1GHz~60GHz频段的RF MEMS单刀十掷开关。该开关采用三角形上电极结构,以减小悬臂梁等效弹性系数和闭合接触面积,达到低驱动电压、高隔离度的目的。通过渐进传输线结构,改善阶跃补偿引起的信号损耗问题。仿真结果显示:该单刀十掷开关的驱动电压为13V,在1GHz~60GHz频段范围内,输入端两侧输出端口的插入损耗<2dB,其余八个端口插入损耗≤0.59dB,所有端口隔离度均>30dB。此开关可适用于无线通信系统、雷达系统和仪器测量系统等对射频性能要求高的领域内。

Effects of back gate bias on radio-frequency performance in partially depleted silicon-on-inslator nMOSFETs

The effects of back gate bias(BGEs) on radio-frequency(RF) performances in PD SOI n MOSFETs are presented in this paper. Floating body(FB) device, T-gate body-contact(TB) device, and tunnel diode body-contact(TDBC) device, of which the supply voltages are all 1.2 V, are compared under different back gate biases by different figures of merit, such as cut-off frequency( fT), maximum frequency of oscillation( fmax), etc. Because of the lack of a back gate conducting channel, the drain conductance(gd) of TDBC transistor shows a smaller degradation than those of the others, and the trans-conductance(gm) of TDBC is almost independent of back gate bias. The values of fT of TDBC are also kept nearly constant under different back gate biases. However, RF performances of FB and TB each show a significant degradation when the back gate bias is larger than ～ 20 V. The results indicate that TDBC structures could effectively improve the back gate bias in RF performance.

DC—20GHz RF MEMS Switch

The design and fabrication of a RF MEMS switch is reported for the first time in China.The switching element consists of a thin metallic membrane,which has the metal-isolator-metal contact and a capacitive shunt switch as single-pole single-throw.When an electrostatic potential is applied to the membrane and the bottom electrode,the attractive electrostatic force pulls the metal membrane down onto the bottom dielectric.The switch characteristics,such as insertion loss and isolation,depend on the off and on-capacitance.The test results are as follows:the pulldown voltage is about 20V;the insertion loss is less than 0 69dB from DC to 20GHz in the up-state;the isolation is more than 13dB from 14 to 18GHz and 16dB from 18 to 20GHz in the down-state.

Thermal Effects and RF Power Handling of DC～5GHz MEMS Switch

A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.

RF MEMS Switch on Poly-Silicon Substrate

The improvements of the design and the compatibility with silicon IC of RF MEMS switch are presented.The compatibility with silicon IC is realized by dielectric isolation technology,and the decrease of the pull voltage of the switch is done by etching some holes on the metal membrane.The preliminary test results are as follows: C off and C on are 0 32pF,6pF,respectively;the pull down voltage is about 25V.The package of the RF MEMS switch is done by micro stripline,and the isolation and the insertion loss are 35dB,2dB,respectively at 1 5GHz;the switching speed is about 3μs by oscilloscope.

Effect of Inertial Shock on RF MEMS Capacitive Switches Property in Low Vacuum

The influence of outside inertial shock combined with RF signal voltages on the properties of a shunt capacitive MEMS switch encapsulated in a low vacuum environment is analyzed considering the damping of the air around the MEMS switch membrane. An analytical expression that approximately computes the displacement induced by outside shock is obtained. According to the expression, the minimum required mechanical stiffness constant of an MEMS switch beam in some maximum tolerated insertion loss condition and some external inertial shock environment or the insertion loss induced by external inertial shock can also be obtained. The influence is also illustrated with an RF MEMS capacitive switch example,which shows that outside environment factors have to be taken into account when designing RF MEMS capacitive switches working in low vacuum. While encapsulating RF MEMS switches in low vacuum diminishes the air damping and improves the switch speed and operation voltage,the performances of a switch is incident to being influenced by outside environment. This study is very useful for the optimized design of RF MEMS capacitive switches working in low vacuum.

一种X波段三叉H型低电压RF MEMS开关设计

针对射频电路系统所需要的低电压,高隔离度,低插入损耗的应用需求,通过对开关正对面积对驱动电压产生的影响进行探究,设计了一款应用于X波段三叉H型的RF MEMS开关。开关具有六条悬臂梁作为支撑,通过增大上极板面积来降低开关的开启电压。分别使用HFSS和COMSOL对开关的射频性能和机械性能进行仿真,开关最终优化后,在8-12 GHz内,插入损耗为0.26~0.57 dB,隔离度大于31.30 dB。在10.1 GHz达到最优值,插入损耗为0.40 dB,隔离度为50.25 dB。开关电压在11V时就能够实现状态转换,开关的响应时间为18μs。此开关可与射频可重构器件结合,应用于新一代射频微波领域。

High-performance RF Switch in 0.13 μm RF SOI process

A high-performance single-pole single-throw(SPST) RF switch for mobile phone RF front-end modules(FEMs) was designed and characterized in a 0.13 μm partially depleted silicon-on-insulator(PD SOI) process. In this paper, the traditional seriesshunt configuration design was improved by introducing a suitably large DC bias resistor and leakage-preventing PMOS, together with the floating body technique. The performance of the RF switch is greatly improved. Furthermore, a new Ron × Coff testing method is also proposed. The size of this SPST RF switch is 0.2 mm2. This switch can be widely used for present 4 G and forthcoming 5 G mobile phone FEMs.

Sensitivity analysis of pull-in voltage for RF MEMS switch based on modified couple stress theory

An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam and a modified couple stress theory, and is validated by comparison with the finite element results. The sensitivity functions of the pull-in voltage to the designed parameters are derived based on the proposed model. The sensitivity investigation shows that the pull-in voltage sensitivities increase/decrease nonlinearly with the increases in the designed parameters. For the stepped cantilever beam, there exists a nonzero optimal dimensionless length ratio, where the pull-in voltage is insensitive. The optimal value of the dimensionless length ratio only depends on the dimensionless width ratio, and can be obtained by solving a nonlinear equation. The determination of the designed parameters is discussed, and some recommendations are made for the RF MEMS switch optimization.

Rydberg electromagnetically induced transparency and Autler–Townes splitting in a weak radio-frequency electric field

We utilize an electromagnetically induced transparency(EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6 S_(1/2)–6 P_(3/2)–66 S_(1/2) scheme, to investigate the Autler–Townes(AT)splitting resulting from a 15.21-GHz radio-frequency(RF) field that couples the |66 S_(1/2) → |65 P_(1/2) Rydberg transition.The radio-frequency electric field induced AT splitting, γAT, is defined as the peak-to-peak distance of an EIT-AT spectrum.The dependence of AT splitting γAT on the probe and coupling Rabi frequency, ?_p and ?_c, is investigated. It is found that the EIT-AT splitting strongly depends on the EIT linewidth that is related to the probe and coupling Rabi frequency in a weak RF-field regime. Using a narrow linewidth EIT spectrum would decrease the uncertainty of the RF field measurements.This work provides new experimental evidence for the theoretical framework in [J. Appl. Phys. 121, 233106(2017)].

A 0.5–3.0 GHz SP4T RF switch with improved body self-biasing technique in 130-nm SOI CMOS

A single-pole four-throw(SP4T)RF switch with charge-pump-based controller is designed and implemented in a commercial 130-nm silicon-on-insulator(SOI)CMOS process.An improved body self-biasing technique based on diodes is utilized to simplify the controlling circuitry and improve the linearity.A multistack field-effect-transistor(FET)structure with body floating technique is employed to provide good power-handling capability.The proposed design demonstrates a measured input 0.1-d B compression point of 38.5 d Bm at 1.9 GHz,an insertion loss of 0.27 d B/0.33 d B and an isolation of 35 d B/27 d B at 900 MHz/1.9 GHz,respectively.The overall chip area is only 0.49 mm^2.This RF switch can be used in GSM/WCDMA/LTE frontend modules.

A novel low-loss four-bit bandpass filter using RF MEMS switches

This paper details the design and simulation of a novel low-loss four-bit reconfigurable bandpass filter that integrates microelectromechanical system(MEMS)switches and comb resonators.A T-shaped reconfigurable resonator is reconfigured in a'one resonator,multiple MEMS switches'configuration and used to gate the load capacitances of comb resonators so that a multiple-frequency filtering function is realized within the 7-16 GHz frequency range.In addition,the insertion loss of the filter is less than 1.99 dB,the out-of-band rejection is more than 18.30 dB,and the group delay is less than 0.25 ns.On the other hand,the size of this novel filter is only 4.4 mm×2.5 mm×0.4 mm.Our results indicate that this MEMS reconfigurable filter,which can switch 16 central frequency bands through eight switches,achieves a low insertion loss compared to those of traditional MEMS filters.In addition,the advantages of small size are obtained while achieving high integration.

Preparation and Characterization of Transparent Conductive Zinc Doped Tin Oxide Thin Films Prepared by Radio-frequency Magnetron Sputtering

High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic target.The effect of substrate temperature on the structural,electrical and optical performances of ZTO films has been studied.X-ray diffraction （XRD） results show that ZTO films possess tetragonal rutile structure with the preferred orientation of （101）.The surface morphology and roughness of the films was investigated by the atomic force microscope （AFM）.The electrical characteristic （including carrier concentration,Hall mobility and resistivity） and optical transmittance were studied by the Hall tester and UV- VIS,respectively.The highest carrier concentration of -1.144×1020 cm-3 and the Hall mobility of 7.018 cm2（V ·sec）-1 for the film with an average transmittance of about 80.0% in the visible region and the lowest resistivity of 1.116×10-2 Ω·cm were obtained when the ZTO films deposited at 250 oC.

减少静电漂移的高可靠RF MEMS开关研究

RF MEMS开关具有制作工艺简单、易于集成等优点。而目前由电介质膜电荷积累造成的静电漂移及频繁机械碰撞导致严重的可靠性问题阻碍了其嵌入终端射频系统稳定性的提高。因此结构上采用电介质悬空薄膜改善电荷积累问题,并对开关机械结构限位实现开关的动态缓冲,降低高频次的机械碰撞损伤。同时依靠凸台触点结构,减少静电漂移。确立了电介质膜充电、开关寿命的理论模型并预测开关的寿命。结果表明,所设计开关寿命超过12900 h。相比已有RF MEMS开关,在两极板间距及金属梁-电介质膜间距分别相等的情况下,所提出的开关结构,寿命分别提高253倍和166倍,极大地改善静电漂移问题。在52.2 GHz工作频率下,隔离度为-41.31 dB,损耗为-0.25 dB,响应时间为50μs,为高性能、高可靠、长寿命射频开关提供了理论模型。

Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow

In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed; under the supersonic inflow, the plasma is blown downstream but remains continuous and stable.Time-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow.

Measurement Process of MOSFET Device Parameters with VEE Pro Software for DP4T RF Switch

To design a Double-Pole Four-Throw (DP4T) RF switch, measurement of device parameters is required. In this DP4T RF switch CMOS is a unit cell, so with a thin oxide layer of thickness 628 ? which is measured optically. Some of the material parameters were found by the curve drawn between Capacitance versus Voltage (C-V) and Capacitance versus Frequency (C-F) with the application of Visual Engineering Environment Programming (VEE Pro). To perform the measurement processing at a distance, from the hazardous room, we use VEE Pro software. In this research, to acquire a fine result for RF MOSFET, we vary the voltage with minor increments and perform the measurements by vary the applying voltage from +5 V to –5 V and then back to +5 V again and then save this result in a data sheet with respect to temperature, voltage and frequency using this program. We have investigated the characteristics of RF MOSFET, which will be used for the wireless telecommunication systems.

Influence of Discharge Parameters on Tuned Substrate Self-Bias in an Radio-Frequency Inductively Coupled Plasma

The tuned substrate self-bias in an rf inductively coupled plasma source is controlled by means of varying the impedance of an external LC network inserted between the substrate and the ground. The influencing parameters such as the substrate axial position, different coupling coils and inserted resistance are experimentally studied. To get a better understanding of the experimental results, the axial distributions of the plasma density, electron temperature and plasma potential are measured with an rf compensated Langmuir probe; the coil rf peak-to-peak voltage is measured with a high voltage probe. As in the case of changing discharge power, it is found that continuity, instability and bi-stability of the tuned substrate bias can be obtained by means of changing the substrate axial position in the plasma source or the inserted resistance. Additionally, continuity can not transit directly into bi-stability, but evolves via instability. The inductance of the coupling coil has a substantial effect on the magnitude and the property of the tuned substrate bias.

Characterization Process of MOSFET with Virtual Instrumentation for DP4T RF Switch – A Review

With the increasing interest in radio frequency switch by using the CMOS circuit technology for the wireless communication systems is in demand. A traditional n-MOS Single-Pole Double-Throw (SPDT) switch has good performances but only for a single operating frequency. For multiple operating frequencies, to transmitting or receiving information through the multiple antennas systems, known as MIMO systems, it a new RF switch is required which should be capable of operating with multiple antennas and frequencies as well as minimizing signal distortions and power consumption. We already have proposed a Double-Pole Four-Throw (DP4T) RF switch and in this research article we are discussing a process for the characterization of the MOSFET with Virtual Instrumentation. The procedure to characterize oxide and conductor layers that are grown or deposited on semiconductors is by studying the characteristics of a MOS capacitor that is formed of the conductor (Metal)-insulator-semiconductor layers for the purpose of RF CMOS as a switch is presented. For a capacitor formed of Metal-silicon dioxide-silicon layers with a thick oxide measured opti-cally. Some of the calculated material parameters are away from the expected values. These errors might be due to several factors such as a possible offset capacitance of the probes due to improper contact with the wafer which is measured by using the LCR (Inductance-Capacitance-Resistance) meter with the help of Visual Engineering Environment Programming (VEE Pro, a Agilent product).

Capacitive Model and S-Parameters of Double-Pole Four-Throw Double-Gate RF CMOS Switch

In this paper, we have analyzed the Double-Pole Four-Throw Double-Gate Radio-Frequency Complementary Metal-Oxide-Semiconductor (DP4T DG RF CMOS) switch using S-parameters for 1 GHz to 60 GHz of frequency range. DP4T DG RF CMOS switch for operation at high frequency is also analyzed with its capacitive model. The re-sults for the development of this proposed switch include the basics of the circuit elements in terms of capacitance, re-sistance, impedance, admittance, series equivalent and parallel equivalent of this network at different frequencies which are present in this switch whatever they are ON or OFF.