Robert Malmqvist

Switched Beam Antenna Based on RF MEMS SPDT Switch on Quartz Substrate

This letter demonstrates a 20-GHz radio frequency microelectromechanical system (RF MEMS)-based electrically switchable antenna on a quartz substrate. Two quasi-Yagi antenna elements are monolithically integrated with a single-pole double-throw (SPDT) MEMS switch router network on a 21 mm times 8 mm chip. Electrical beam steering between two opposite directions is achieved using capacitive MEMS SPDT switches in the router. Port impedance and radiation patterns are studied numerically and experimentally. Measured results show that the switched beam antenna features a 27% impedance bandwidth (S11 = -10 dB), a gain of 4.6 dBi, and a front-to-back ratio of 14 dB at 20 GHz when the control voltage is applied to one of the switch pairs of the SPDT switch.

On the Use of MEMS Phase Shifters in a Low-Cost Ka-band Multifunctional ESA on a Small UAV

We present a system concept for a Ka-band multi-functional electronically steerable antenna (ESA) on a small UAV that is based on using sub-arrays with low-loss RF MEMS phase shifters. Our analysis shows that low phase shifter losses are critical if the dissipated radar hardware DC power should fit within the given requirements. The results presented in this paper also indicate that adequate performance (in terms of 2 dB of average losses at 35 GHz) can be possible to achieve with a Ka- band 4-bits MEMS phase shifter design made on quartz.

RF MEMS and GaAs Based Reconfigurable RF Front-End Components for Wide-Band Multi-Functional Phased Arrays

We study possibilities of implementing flexible and programmable components for the RF front-ends of wideband multi-functional phased arrays using GaAs MMIC and RF MEMS technologies. The use of MEMS reconfigurable matching networks in tunable bandpass LNAs is proposed to achieve wider tuning ranges (e.g. 6.5-9.9 GHz is obtained according to simulations) and adequate performance of such LNAs. We further demonstrate the potential for monolithic integration with active devices by showing how variable MEMS capacitors may be realized in a GaAs foundry process

RF MEMS and MMIC based reconfigurable matching networks for adaptive multi-band RF front-ends

In this paper, we present GaAs MMIC based reconfigurable RF MEMS impedance matching networks for highly integrated (potentially single-chip) frequency-agile LNAs and adaptive multi-band front-ends. Such GaAs MMIC based RF MEMS LNA matching networks have been realized with a frequency tuning range of 40% (10-16 GHz and 15-23 GHz, respectively) and 1-3 dB of in-band losses. Simulated tunable LNA results based on measured data of GaAs MMIC MEMS matching circuits (and simulated data of MEMS matching networks made on quartz) show the potential of achieving a high gain and low in-band noise figure over such wide tuning ranges.

RF MEMS based impedance matching networks for tunable multi-band microwave low noise amplifiers

In this paper, we present different types of reconfigurable RF MEMS based matching networks intended for frequency-agile (multi-band) LNAs. Measured results of 2-bits matching networks show a centre frequency tuning range of 2–3 GHz (10–13%) around 20 GHz and 1.5–2.0 dB of minimum losses. Simulated tunable LNA results based on measured data of the RF MEMS matching networks show the possibilities of achieving similar high gain, good matching and low NF over the whole tuning range. The results demonstrate the potential of using RF MEMS switches for the realization of tunable LNAs at microwave and millimetre-wave frequencies.

Ka-band RF MEMS phase shifters for energy starved millimetre-wave radar sensors

Low-loss millimetre-wave RF MEMS phase shifters made on quartz are assessed with respect to a Ka-band low-power multifunctional radar sensor application. A loaded line type of phase shifter circuit presents a phase shift of 22.3° and a loss of 0.4 dB at 35 GHz. A switched line phase shifter gives 187° of phase shift and 1.5 dB of loss at 30 GHz (i.e. a FoM=122°/dB). We estimate that a 5-bit loaded line/switched line MEMS phase shifter circuit can achieve a loss of 4 dB at 35 GHz which could reduce by a factor 2 the required transmit DC power level in a Ka-Band energy starved phased array radar system.

Self-actuation tests of ohmic contact and capacitive RFMEMS switches for wideband RF power limiter circuits

This paper presents an experimental study on the high power handling capabilities of some ohmic contact based and capacitive RF-MEMS switches (incl. self-actuation tests made up to 18 GHz). Such tests carried out on a series and shunt connected ohmic contact COTS MEMS switch show that self-actuation occurred at 29-37 dBm of RF input power (Pin) given a DC bias (Vbias) of 42-47 V. Corresponding high power tests of a capacitive MEMS switch made on quartz (at 4 GHz) show that self-actuation occurred at Pin = 24-31 dBm with Vbias = 0-19 V. The experimental results further indicate a potential usefulness of employing ohmic contact and capacitive MEMS switches to realize optimised low-loss wideband power limiter circuits.

A K-band single-chip reconfigurable/multi-functional RF-MEMS switched dual-LNA MMIC

A K-band (18–26.5 GHz) single-chip reconfigurable and multi-functional RF-MEMS switched dual-LNA MMIC (optimized for lowest/highest possible noise figure/linearity) is presented. The two MEMS switched low-NF and high-linearity LNA circuit functions present 18.6 dB/9.0 dB, 2.4 dB/3.5 dB and 22 dBm/29 dBm of small-signal gain, noise figure and OIP3 at 20 GHz, respectively. The in-band isolation levels of the two switched LNA paths equal 16–20 dB when the MEMS switches are switched on and off. Compared with two fixed (non-reconfigurable) LNA breakout circuits, the MEMS switched LNA circuit functions show 0.5–1.0 dB higher NF together with similar values of linearity at 15–25 GHz.

Monolithic integration of millimeter-wave RF-MEMS switch circuits and LNAs using a GaAs MMIC foundry process technology

Wideband millimeter-wave RF-MEMS switch networks and active RF circuits have been monolithically integrated on the same GaAs wafer using an MMIC foundry process technology. GaAs MEMS SPST and SPDT switches present below 1 dB of insertion loss and more than 8 dB/20 dB of isolation up to 75 GHz and 40 GHz, respectively. A compact 1-bit Ka-band GaAs MEMS phase shifter circuit achieve a high figure-of-merit with respect to low in-band losses for a given phase shift. The demonstrated on-wafer integration of two wideband LNAs further show the capabilities of realizing highly integrated (single-chip) reconfigurable active RF-MEMS based MMICs and front-ends at millimeter-wave frequencies.

A 7.9-9.7 GHz on-chip radar receiver front-end for future adaptive X-band smart skin array antennas

In this paper, we present a 7.9-9.7 GHz on-chip radar receiver front-end intended for a digital beamforming X-band smart skin phased array antenna. This agile single-chip receiver front-end could potentially enable a significant size and cost reduction of the microwave receiver modules in such an adaptive frequency hopping radar system. Measured results show a close to adequate performance.