RF Matching Network Research Articles

A S-band switchless bi-directional transceiver with a 52% fractional bandwidth in CMOS technology

This paper presents a bi-directional switchless wideband transceiver front-end for S-band multi-functional digital array system. In an S-band digital array system, a silicon-based RF front-end module requires a high integration level, compact size, large bandwidth, and low power consumption features. A bi-directional switchless transceiver could provide a compact solution. However, the shared RF matching network in such a transceiver is crucial due to its influence on Rx sensitivity, Tx output power, TRx isolation, and bandwidth. This work proposes a compact π matching network for simultaneous broadband Rx noise matching, Tx power matching, and TRx isolation. Also, a double quadrature down-conversion architecture is proposed to improve image signal rejection in the whole S-band. Therefore, false detection in the S-band digital array can be avoided. Fabricated in a 0.18μm CMOS technology, this S-band transceiver occupies a silicon area of 3.2 × 2 mm2. In the Rx mode, the measured gain is 20.7–28 dB in 2–4 GHz at 25 °C. The RX noise figure is 9.5–11.5 dB, and the input 1-dB compression point is -11 dBm. In the Tx mode, the gain is 16.5–19.6 dB in 2–4 GHz at 25 °C, and Psat is 10.2 dBm. The RX bandwidth is 2–3.4 GHz, while that of Tx is 2–4 GHz. The corresponding fractional bandwidth is 52% and 67%, respectively. Furthermore, this transceiver shows an image rejection ratio of 28.9–41.4 dB suppression at the operation frequency band.

A Hybrid GA/ML-Based End-to-End Automated Methodology for Design Acceleration of Wireless Communications CMOS LNAs

A new methodology for the RF/mmWave analog design process, automation and acceleration, is presented in this work. The proposed framework was implemented so as to accelerate the design cycle of analog/RF circuits by creating a dataset in a fully automated manner and training a combination of machine learning models for the optimal design parameters’ prediction. machine learning polynomial regression was adopted to accelerate the design process, predicting the optimal design parameters’ values while genetic algorithm optimization was exploited for the dataset creation automation. To evaluate the efficiency of the proposed methodology, the framework was implemented for the design of a common source Low-Noise-Amplifier, using a 65 nm CMOS process node. The proposed methodology successfully tackles the design cycle speed-up, automation, and acceleration, utilizing machine learning prediction for the design parameters and genetic algorithm for the dataset creation automation instead of the classical, simulation-based, standard design methodology. The provided experimental results have shown the effectiveness of the proposed hybrid approach, creating very precise RF matching networks for LNA designs and achieving >99.9% wave transmission efficiency while reaching >99% accuracy on the parameters’ prediction task.

AV-Band Ultra Low Power Sub-HarmonicI/QDown-Conversion Mixer Using Current Re-Used Technique

In this brief, we present a low power sub-harmonic I/Q mixer using the current re-used technique for WiGig at 60 GHz. A transformer integrates the RF trans-conductance stage and LO switching stage by the current re-used technique to save dc power. We only adopt a single transistor at RF stage to replace differential RF amplifier to save die area as only half of the RF matching network is required. The trans-conductance of the RF stage is increased by the $g_{m}$ -boost technique. In addition, since the current re-used technique gathering the dc current from both ${I}$ and ${Q}$ mixer cores, the transconductance of the RF stage is also increased. In order to reduce the die area of passive components, we use mutually coupled inductors to implement lumped element Wilkinson power divider. We also add extra capacitors on all ports of the coupler to improve return loss. The measured peak gain is −7.9 dB at 61 GHz under LO power of 5 dBm at 30 GHz. The measured IP1dB is better than −9.5 dBm in four channels. The measured 3-dB RF bandwidth is from 56.5-67 GHz and 3-dB IF bandwidth is 1.5 GHz. Total dc power consumption is only 3.45 mW and each mixer consumes 1.73 mW for 1.1 V supplied voltage. To our best knowledge, this current re-used I/Q mixer has the lowest dc power and good conversion gain among active I/Q mixers at ${V}$ -band.

An easily reproducible, hand-held, single-sided, MRI sensor.

Single-sided MRI sensors allow the imaging of samples that are larger than the magnet. Thus, they enable truly portable imagers with potential applications in medicine, quality assurance (QA), agriculture, material science, and other fields. However, despite recent advancements, single-sided MRI systems are relatively uncommon. This is partially due to the limited number of commercial products. Also, current implementations often require large and/or complex magnet arrays which require machining techniques such as milling or drilling. These techniques must be performed to tight tolerances to ensure accuracy of the B0 field. Furthermore, these systems generally have hand-wound RF or gradient coils that are not trivial to construct. The main goals of this work are to reduce the size of single-sided MRI sensors while simultaneously making them more accessible for others to build. To this end, we present a hand-held, single-sided, MRI sensor that is constructed using an easy-to-assemble magnet array, a 3D-printed housing, and printed circuit boards (PCBs) that contain the RF coil, gradient coils, and matching network. By implementing all coils directly on PCBs, the geometry can be easily optimized and then manufactured at low cost. Both spin density-weighted and T1-weighted images of various samples are presented to demonstrate the capabilities of the proposed sensor.

Modular Design of RF Front End for a Nanosatellite Communication Subsystem Tile Using Low-Cost Commercial Components

In recent years, the development market for low-cost nanosatellites has grown considerably. It has been made possible due to the availability of low-cost launch vectors and the use of “commercial off-the-shelf components” (COTS). The satellite design standardization has also helped a great deal to encourage subsystem reuse over a number of space missions. This has created numerous opportunities for small companies and universities to develop their own nanosatellite or satellite subsystems. Most COTS components are usually not space qualified. In order to make them work and withstand the harsh space environment, they need extra effort in circuit redesign and implementation. Also, by adopting the modularity concept and the design reuse method, the overall testing and nonrecurring development cost can be significantly reduced. This can also help minimize the subsystem testing times. The RF front-end design presented in this paper is also considered one of the better and feasible choices based on the above approach. It consists of an S-band transceiver that is fully implemented using COTS components. In the transmit chain, it is comprised of the transmitting CC2510 RF matching network and a power amplifier (PA) with an RF output power of up to 33 dBm which connects to an antenna using two RF switches. The receive chain starts from the antenna that is connected through two RF switches to the low-noise amplifier (LNA) that further connects to the receiving CC2510 via the RF matching network. The receiver sensitivity is -100 dBm. This is a half-duplex system using the same antenna for transmitting and receiving. The receiver and transmitter chains are isolated together using two RF switches which together provide an isolation of up to 90 dB at 2.4 GHz. The concept behind using two RF switches is to provide better isolation from the transmit chain to the LNA. The matching network of CC2510 has been designed in a symmetric fashion to avoid any delays. All the RF COTS used have been selected according to link budget requirements. The LNA, PA, and RF switches were tested individually for compliance. The passive components used in the overall design of the matching network are chosen on the basis of minimum dimension, least parasitic behaviour, and guaranteed optimum RF matching. Also, the RF COTS used are non-CMOS which makes them more robust against space radiations associated with the LEO environment and enables them to provide a radio communication data rate of up to 500 kbps in both uplink and downlink. The vacant spaces on the implemented PCB are shielded with a partial ground plane to avoid RF interference.

A Wake-Up Receiver With a Multi-Stage Self-Mixer and With Enhanced Sensitivity When Using an Interferer as Local Oscillator

An ultra-low power wake-up receiver with an energy-detection passive-RF architecture uses a multi-stage self-mixer that has a better conversion gain than the conventional envelope detector. The self-mixer, co-designed with the RF matching network, optimizes the sensitivity and minimizes the power consumption of the receiver. A wake-up receiver prototype in 0.13- $\mu \text{m}$ CMOS operates at 550 MHz, consumes 220 nW from 0.5 V, and achieves a sensitivity of −56.4 dBm at a 400-kb/s chip rate using an 11-bit wake-up code. When a large interferer is present, the receiver operates in an interferer-enhanced mode, leveraging the interferer as a local oscillator to improve the sensitivity; in the presence of a −43.5-dBm interferer, a −63.6-dBm sensitivity is achieved while consuming 1.1 $\mu \text{W}$ .

Novel Planar and Waveguide Implementations of Impedance Matching Networks Based on Tapered Lines Using Generalized Superellipses

For the practical implementation of RF and microwave impedance matching networks, a widely employed solution—alternative to the use of classical impedance transformers—is based on tapered lines. This paper shows a simple method to design smooth tapers that take into account the dispersion of the line and the required design bandwidth simultaneously. A planar taper has been designed in microstrip technology with the same length of classical ones but improving their performances. A waveguide prototype has also been designed with similar performance to a commercial one but with one third of its length. Both tapered structures have been obtained through the optimization of very few parameters using the same design strategy. As a result, the reflection coefficient of the tapers can be optimally adapted to a given specific mask using the prescribed value of physical length. Experimental results for both tapers are included for the validation of the proposed topologies and the related design method.

Complex interaction of passive multiport structures and their description by separate discrete models

It is demonstrated, using the example of a T-junction, that not every multiport structure can be accurately described by a discrete and separated modelling approach at millimetre and sub-millimetre wavelengths. It is shown that especially stub-networks, which are typically used in RF-matching networks, are affected. In this case, the discrete modelling approach predicts a different resonance frequency than the S-parameter measurement as well as the 3D electromagnetic field simulation (3D-EMFS) of the whole structure. However, these resonances are of particular importance for the design of a RF matching network and should be predicted by the model as precisely as possible. Therefore, the reason for the mismatch by accurate 3D-EMFS is investigated and a possible solution on how to model the so-called complex interactions in passive multiport structures at millimetre and sub-millimetre wavelengths is provided.

Characterization of the CW starter plasma RF matching network for operating the SNS H⁻ ion source with lower H₂ flows.

The Spallation Neutron Source H(-) ion source is operated with a pulsed 2-MHz RF (50-60 kW) to produce the 1-ms long, ∼50 mA H(-) beams at 60 Hz. A continuous low power (∼300 W) 13.56-MHz RF plasma, which is initially ignited with a H2 pressure bump, serves as starter plasma for the pulsed high power 2-MHz RF discharges. To reduce the risk of plasma outages at lower H2 flow rates which is desired for improved performance of the following radio frequency quadrupole, the 13.56-MHz RF matching network was characterized over a broad range of its two tuning capacitors. The H-α line intensity of the 13.56-MHz RF plasma and the reflected power of the 13.56-MHz RF were mapped against the capacitor settings. Optimal tunes for the maximum H-α intensity are consistent with the optimal tunes for minimum reflected power. Low limits of the H2 flow rate not causing plasma outages were explored within the range of the map. A tune region that allows lower H2 flow rate has been identified, which differs from the optimal tune for global minimum reflected power that was mostly used in the past.

Design of a RF matching network based on a new tunable inductor concept

We present in this paper a new technique of matching impedances. It consists in replacing a fixed inductor in a matching network by a variable one, and its value is able to change with the load impedance. In the study, the fixed inductance considered is a CMOS integrated one, while the tunable inductance is based on a new Piezomagnetic MEMS concept. A theoretical model of such a tunable inductor is first presented, and then inserted in a matching network in two different ways: inductance value varies either discretely or continuously. The obtained matching networks are compared with a fixed inductor matching network, and simulation results are presented and discussed to validate the presented method and to evaluate the matching efficiency of each matching network.

Cgs compensating V-band resistive mixer with low conversion loss at low LO power

A C gs compensating resistive mixer with low conversion loss at a low LO power level is proposed. In the proposed mixer with an additional transistor, C gs looking at the gate applying an LO signal is reduced by C gd , C gs , and C ds of the additional transistor. This enables the proposed resistive mixer to have low conversion loss at a low LO power level. This enables the circuit to have high LO-RF isolation and facilitates an RF and IF matching network design. The fabricated chip size using 0.13 m CMOS technology is 0.71 × 0.69 mm 2 . It achieves a conversion loss of 6.2 to 9.7 dB at an RF frequency of 56 to 63 GHz, and an input P 1dB of -2.5dBm at an LO power of 0dBm. This is believed to be the lowest conversion loss among V-band resistive mixers.

A Low-Power 2.4-GHz CMOS GFSK Transceiver With a Digital Demodulator Using Time-to-Digital Conversion

A technique of time-to-digital conversion is utilized in a digital demodulator for a low-power 2.4-GHz CMOS GFSK transceiver. The proposed time-to-digital converter (TDC) employs a self-sampling technique and an auto-calibration algorithm to avoid edge synchronization problems and the need of a delay-locked loop (DLL). With the TDC, a limiter and a digital demodulator can be employed simultaneously in the receiver to achieve low power consumption and high performance. Additionally, in the transmitter, the open-loop VCO modulation is adopted to save hardware and power consumption. The transmitter frequency drift in open-loop modulation and frequency offset between the receiver and the transmitter can be easily resolved by the proposed receiver architecture. All required building blocks of the proposed transceiver, except a RF matching network and a crystal, were implemented on a 4-mm2 chip by a 0.18-?m CMOS process. The receiver achieves -89 -dBm sensitivity at 0.1% BER with 1-Mb/s data rate, and the transmitter delivers up to 0-dBm output power. The receiver and transmitter consume 13.3 mA and 10.7 mA, respectively, from a 1.8-V power supply.

On-chip transformer-based feedback CMOS power oscillator

A fully on-chip transformer-based feedback CMOS power oscillator is presented. Using only one on-chip transformer to reduce Si substrate loss of RF feedback, matching and bias networks, a maximum DC-to-RF conversion efficiency of ∼66% with an output RF power of ∼15.33 dBm and a phase noise of ∼−113 dBc/Hz at 100 kHz offset from carrier 2.45 GHz is achieved.

Rf probe technology for the next generation of technologicalplasmas

We describe radio frequency (rf) analysis of technological plasmasat the 13.56 MHz fundamental drive frequency and integer narrow-band harmonicsup to n = 9. In particular, we demonstrate the use of harmonic amplitudeinformation as a process end-point diagnostic. Using very high frequency (vhf)techniques, we construct non-invasive ex situ remote-coupled probes: adiplexer, an equal-ratio-arm bridge, and a dual directional coupler used as asingle directional device. These probes bolt into the plasma-tool 50 Ωtransmission-line between the rf generator and matching network, and hence donot require modification of the plasma tool. The 50 Ω probe environmentproduces repeatable measurements of the chamber capacitance and narrow-bandharmonic amplitude with an end-point detection sensitivity corresponding to a2 dB change in the harmonic amplitude with the removal of 1 cm2 of photoresist.The methodology and design of an instrument for the measurement of theplasma-tool frequency response, and the plasma harmonic amplitudeand phase response are examined. The instrument allows the monitoring of theplasma phase delay, plasma-tool short- and long-term ageing, and processend-point prediction.

Construction and Commissioning of a 100 KW RF Amplifier System for Hanbit Central Cell Plasma Heating

To complete basic configuration for the RF heating scenario in Central Cell of the Hanbit mirror device, a RF amplifier system with a power of 100 kW and frequency range of 1.4 – 4.0 MHz, and a high power RF matching network have been developed in KBSI. The output pulse width of the amplifier ranges from 10 msec to 100 msec and the duty cycle is 100 msec/300 sec. The developed amplifier will be used for plasma production and heating by utilizing the slot antenna and the double-half-turn antenna, respectively.In this paper, we present the engineering design of the amplifier system and matching network, and experimental results such as power test of amplifier on dummy load, impedance matching test on the double-half-turn antenna in vacuum condition. Also, the first RF launching experiment result with the double-half-turn antenna on the target plasma which is produced by the slot antenna is presented.

Problems of Power Feeding in Large Area PECVD of Amorphous Silicon

AbstractThe production of amorphous silicon, e.g. for solar cells, requires large area, high-deposition rate plasma reactors. Increasing the radio frequency from the conventional 13.56MHz up to VHF has demonstrated higher deposition and etch rates and lower particle generation, a reduced ion bombardement and lower breakdown, process and bias voltages.But otherwise the use of VHF leads to some problems. The non-uniformity of deposition rate increase due to the generation of standing waves (TEM wave) and evanescent waveguide modes (TE waves) at the electrode surface.Increasing the frequency and/or the deposition area the plasma impedance, the capacitic stray impedance of the RF electrode and other parasitic capacitive impedances decrease. Increasing the frequency and/or the RF power, the phase angle of the discharge and of the impedance at every point at the lines between the RF matching network an the RF electrode tends more and more towards -90°. This results in increasing currents and standing waves with extremly high local current maximas. Increasing resistances of lines and contacts due to the skin effect and loss-caused heating up of the lines the power losses increase extremely, up to 90% and more. In spite of the increasing of the coupled power, the plasma power does not increase. Thermal destructions of the lines due to extreme expansion or melting are possible.Some solutions to reduce the non-uniformity of the deposition rate like multipower feeding, central backside power feeding, electrode segmentation, use of load impedances, published in former publications, will be discussed in connection with several reactor types (coaxial, large area, long plasma source) in view of the efficiency of power coupling and the practical realization. Solutions to minimize the power losses at the lines will be presented.

A 850-GHz waveguide receiver employing a niobium SIS junction fabricated on a 1-μm Si/sub 3/N/sub 4/ membrane

We report on a 850-GHz superconducting-insulator-superconducting (SIS) heterodyne receiver employing an RF-tuned niobium tunnel junction with a current density of 14 kA/cm/sup 2/, fabricated on a 1-/spl mu/m Si/sub 3/N/sub 4/ supporting membrane. Since the mixer is designed to be operated well above the superconducting gap frequency of niobium (2/spl Delta//h/spl ap/690 GHz), special care has been taken to minimize niobium transmission-line losses. Both Fourier transform spectrometer (FTS) measurements of the direct detection performance and calculations of the IF output noise with the mixer operating in heterodyne mode, indicate an absorption loss in the niobium film of about 6.8 dB at 822 GHz. These results are in reasonably good agreement with the loss predicted by the Mattis-Bardeen theory in the extreme anomalous limit. From 800 to 830 GHz, we report uncorrected receiver noise temperatures of 518 or 514 K when we use Callen and Welton's law to calculate the input load temperatures. Over the same frequency range, the mixer has a 4-dB conversion loss and 265 K/spl plusmn/10 K noise temperature. At 890 GHz, the sensitivity of the receiver has degraded to 900 K, which is primarily the result of increased niobium film loss in the RF matching network. When the mixer was cooled from 4.2 to 1.9 K, the receiver noise temperature improved about 20% 409-K double sideband (DSB). Approximately half of the receiver noise temperature improvement can be attributed to a lower mixer conversion loss, while the remainder is due to a reduction in the niobium film absorption loss. At 982 GHz, we measured a receiver noise temperature of 1916 K.

Production evaluation of real-time statistical process control on a sub-0.5 μm inductively coupled metal etch process

The semiconductor manufacturing industry is demanding improved algorithms for the detection and isolation of equipment faults. The real-time statistical process control (RTSPC) algorithm analyzes real-time sensor and actuator data for the detection of such faults. The software was evaluated using SECS-II (Serial Equipment Communication Standard) data from several commercial plasma etchers. These data were used to build statistical models which were then applied to data recorded during subsequent wafer processing. RTSPC was able to detect several faults related to failure of rf matching networks. For one of the rf match failures, the RTSPC alarm preceded the component failure by several weeks. This alarm was correlated to a shift in the critical dimension of wafers processed in this etcher. The statistical data filters included within RTSPC are discussed, as well as the characterization of the real-time data. Emphasis is placed on whether uni-variate, multivariate, or time-varying statistics are required to detect the faults seen on the etchers, and additional algorithms which would enhance the fault detection capability.

The development of an 850 GHz waveguide receiver using tuned sis junctions on 1µm Si3N4 membranes

We report preliminary development work on a 850 GHz SIS heterodyne receiver employing a tuned niobium tunnel junction on a 1 µm Si3N4 supporting membrane. Since the mixer is meant to be operated well above the superconducting gap frequency of niobium (2δ/h њ 690 GHz) special care has been taken to minimize transmission line loss. We have therefore used junctions with an integrated radial stub RF matching network to tune out the large shunt susceptance of the junction and minimize the niobium film absorption loss. Scale model measurements of the waveguide embedding impedance have been made to aid in the design of the choke structure and RF matching network. Detailed Fourier Transform Spectrometer measurements of tuned junctions on both SiO2 and silicon nitride membranes show response up to 1100 GHz and indicate that the absorption loss in the niobium film is in the order of 4–7 dB at 850 GHz, in fairly good agreement with the theoretical loss calculated from the Mattis-Bardeen theory. The junctions have a center frequency of 800 GHz which presents a 6% downshift from the designed value.

A monolithic AlGaAs/InGaAs upconverter IC for K-band wireless networks

This paper is concerned with the design consideration, fabrication process, and performance of a CPW heterojunction FET (HJFET) upconverter MMIC for K-band wireless system applications. To realize a mixer featuring a simple structure with inherently isolated ports, and yet permitting independent port matching and low LO power operation, a "source injection" concept is introduced by treating the FET as a three-port device in which the IF and LO signals are, respectively, applied to the gate and source terminals, and RF signal is extracted from the drain terminal. The upconverter chip incorporates an HJFET as a mixing element, an IF matching network, an LO matching network, an RF matching network, and an output filter. The upconverter can operate with an LO power level as low as -16 dBm for IF signals in 1.5-2.5 GHz band, and LO signals in 20-23 GHz band. Including a 3 dB pass-band insertion loss of the filter, the upconverter exhibits a maximum conversion gain of -6 dB for an IF power of -5 dBm at 1.9 GHz, and an LO power of 10 dBm at 21.5 GHz. LO suppression at IF and RF ports, respectively, is better than 22 dB and 20 dB, and IF suppression at RF port is better than 35 dB.