RF Transceiver Research Articles

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A Fully Self-Contained Logarithmic Closed-Loop Deep Brain Stimulation SoC With Wireless Telemetry and Wireless Power Management

Although closed-loop deep brain stimulation (DBS) promises treatment of many neurological disorders, an implantable system-on-chip (SoC) implementing an effective closed-loop DBS algorithm has not been demonstrated. This work introduces a logarithmic, closed-loop DBS system that detects and processes low-frequency brain field signals to control and adapt stimulation currents. The system records and processes neural signals with four low-noise neural amplifier (LNA) channels, a multiplexed logarithmic ADC, and two high-pass and two low-pass digital logarithmic filters. Logarithmic processing saves power and achieves high dynamic range. A logarithmic domain digital signal processor (DSP) and PI-controller controls eight current stimulator channels and enables closed-loop stimulation. An RF transceiver, a clock generator, and a power harvester are also included in the system to achieve a complete implantable SoC. The 4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 180 nm CMOS prototype consumes a total of 468 μW for recording and processing neural signals, for stimulation, and for two-way wireless communication.

Cooperative Indoor Localization Using 24-GHz CMOS Radar Transceivers

This paper presents the first truly wireless 24-GHz round-trip time-of-flight local positioning frontend with an integrated CMOS transceiver. The transceiver in 130-nm CMOS technology features a novel receiver/transceiver switching concept, which reduces RF losses between the receiver/transmitter and antenna and drastically improves the transmit/receive isolation. The low-power RF transceiver chip was integrated with a digital signal-processing unit and mounted on a circuit board to form a system-level demonstrator of a secondary radar node incorporating synchronization and a distributed localization algorithm. The performance of the self-organizing localization network is evaluated in an indoor setup using comparisons with reference trajectories. Experimental results show a distance precision between the active nodes close to the theoretical optimum that can be achieved with the used signal parameters, as well as an absolute localization error in the centimeter range.

An IQ mismatch calibration and compensation technique for wideband wireless transceivers

An IQ mismatch calibration and compensation technique based on the digital baseband for wideband wireless communication transmitters is proposed. The digital baseband transmits the signal used for IQ mismatch calibration. The signal passes through the RF transmitter path, the calibration loop (which is composed of a square power detector and a band-pass filter in the RF transceiver) and the variable gain amplifier of the receiver. The digital baseband samples the signal for IQ mismatch estimation and compensates for it. Compared with the self-calibration technique in the RF chip, the proposed technique saves area and power consumption for the wireless local area network solution. This technique has been successfully used for the 802.11n system and satisfies the requirement of the standard by achieving over 50 dB image suppression.

Measuring in-home walking speed using wall-mounted RF transceiver arrays.

In this paper we present a new method for passively measuring walking speed using a small array of radio transceivers positioned on the walls of a hallway within a home. As a person walks between a radio transmitter and a receiver, the received signal strength (RSS) detected by the receiver changes in a repeatable pattern that may be used to estimate walking speed without the need for the person to wear any monitoring device. The transceivers are arranged as an array of 4 with a known distance between the array elements. Walking past the first pair of transceivers will cause a peak followed by a second peak when the person passes the second pair of transceivers. The time difference between these peaks is used to estimate walking speed directly. We further show that it is possible to estimate the walking speed by correlating the shape of the signal using a single pair of transceivers positioned across from each other in a hallway or doorframe. RMSE performance was less than 15 cm/s using a 2-element array, and less than 8 cm/s using a 4-element array relative to a gait mat used for ground truth.

Maintaining Consistency between Caches to Improve Overall Performance in Wireless Sensor Networks

Sensor Network (WSN) is an application based network. Wireless Sensor Network has a wide range of potential, practical and useful applications. Majority of such applications require an optimization to the communication among the sensors, so as to serve data in short latency and with minimal energy consumption. The sensor nodes in WSN are battery powered devices that consumes energy during data transmission and processing. Sink node send query messages in network, nodes may or may not reply back to the sinks query messages, but battery dissipates due to processing. Data transmission in WSN consumes more energy than processing therefore it is appropriate to exploit the benefits of caching. Cooperative caching is used for the reduction in the state of non utility of data and decreases the requirement of wireless bandwidth and energy. Cooperative caching which secure sharing of data among various nodes reduces the number of communications over the wireless channels and thus enhances the overall lifetime of a wireless sensor network. To overcome problem of cooperative cache a new technique is proposed which gives better results than existing one. Network simulator NS-2 is used for the simulations. Wireless sensor offers impressive computational resources for processing data. Wireless Sensor networks are self organizer and are deployed in ad-hoc systems. Each node in wireless sensor is consist of multiple types of memory and processing elements, RF transceiver, a power source, sensors and actuators. Wireless Sensor Network is a distributed real time systems. Wireless Sensor Network is a latest technology that has an ability to coordinate a large network into a single network. It is also consist of large number of low cost devices. Wireless Sensor Network is a Light weighted distributed system. There is no need of external infrastructures in wireless sensor network to communicate with other devices. The sensor in wireless sensor networks deployed are self organized and multi hop in nature. The wireless sensor networks consume a lots of energy while transfer data from one device to other. There is need to adjust transfer and sensing rate to avoid energy consumption in wireless sensor networks (5).

The Design of Wireless Sensor Network Node Based on TinyOS

In order to solve the low power issues of wireless sensor networks, this paper designs a wireless sensor network node embedded operating system based on TinyOS. This paper Briefly introduces on the basis of TinyOS, gives the hardware structure diagram and the hardware connection between the low power MCU MSP430 and RF transceiver chip CC2420. what’s more, the design process of system and the program flow diagram are given. The node can be effectively applied in the power requirements where the requirement of wireless communication power is relatively strict.

Mobile Wireless Communications Device with Buffered Cock Distribution Network

The microprocessor generates many digital noises that find their way back from the clock reference input of the microprocessor to the reference clock lines with which the RF circuits are sharing. These digital noises are conductively coupled to the RF circuits, including any RF transceiver, Bluetooth module and other RF circuits, such as a local oscillator and phase locked loop circuits, to cause spurious signals and jitters in the circuits, which in turn, degrade the RF performance or cause a radio to fail certain specifications.

A Security System Design of WSN Based on Nodes Identification

This paper introduces the design and implementation of the safe transmission mechanism of wireless sensor network. This scheme is aimed at reducing node’s cost of computing and communication. Firstly, the WSN will be clustered. Then, encryption key will be generated in the clusters, which is used of data encryption and decryption based on nodes identification to ensure data security. The system uses the wireless microcontroller CC2430/CC2431 to perform the simulation testing for program modules of Chipcon, which integrates CC2420RF wireless RF transceiver. Experimental results show that the new algorithm can increase traffic, node utilization and improve the confidentiality and security of sensor information.

A 900 MHz Zero-IF RF Transceiver for IEEE 802.15.4g SUN OFDM Systems

This paper presents a 900 MHz zero-IF RF transceiver for IEEE 802.15.4g Smart Utility Networks OFDM systems. The proposed RF transceiver comprises an RF front end, a Tx baseband analog circuit, an Rx baseband analog circuit, and a fractional-N frequency synthesizer. In the RF front end, re-use of a matching network reduces the chip size of the RF transceiver. Since a T/Rx switch is implemented only at the input of the low noise amplifier, the driver amplifier can deliver its output power to an antenna without any signal loss; thus, leading to a low dc power consumption. The proposed current-driven passive mixer in Rx and voltage-mode passive mixer in Tx can mitigate the IQ crosstalk problem, while maintaining 50% duty-cycle in local oscillator clocks. The overall Rx-baseband circuits can provide a voltage gain of 70 dB with a 1 dB gain control step. The proposed RF transceiver is implemented in a CMOS technology and consumes 37 mA in Tx mode and 38 mA in Rx mode from a 1.8 V supply voltage. The fabricated chip shows a Tx average power of -2 dBm, a sensitivity level of -103 dBm at 100 Kbps with PER of -11 dBm, and an Rx input IP3 of -2.3 dBm.

Design of 60GHz RF transceiver in CMOS: Challenges and recent advances

With more than 40 years Moore scaling, the speed of CMOS transistors is around 100 GHz. Such fact makes it possible to realize mm-wave circuits in CMOS. However, with the target of achieving broadband and power-efficient operation, 60 GHz CMOS RF transceiver faces severe challenges. After reviewing the technology issues, regarding the 60 GHz applications, this paper discusses design challenges both from the system and the building block levels, and also presents some simulated or measured circuits results.

A Fully Integrated EPC Gen-2 UHF-Band Passive Tag IC Using an Efficient Power Management Technique

We present a system-on-chip passive tag integrated circuit (IC) for secure near-field RF identification applications. The design of the RF transceiver and the digital control of the tag IC are based on the EPCglobal ultrahigh-frequency Gen-2 protocol. A new design technique for the power management of the tag IC is presented, which includes a low-voltage bandgap, a low-dropout regulator with a bias-boosted gain stage, and an adaptive dc limiter. With the proposed design technique, we achieve a high power conversion efficiency of 47% at a low input power of -12 dBm. To support data security, we use one-time programmable (OTP) memory for nonvolatile data storage. The 4-kb (256 × 16 b) OTP memory array is based on a two-transistor (2-T) gate-oxide antifuse that can be programmed with a voltage of less than 6 V. The tag chip was fabricated in a 1-poly 6-metal standard 0.13- μm CMOS process. The power consumption levels of the tag IC are 29.2 and 71.2 μW for the read and programming modes, respectively. The size of the tag chip is 1.1×1 mm2.

Photonic-Based RF Transceiver for UWB Multi-Carrier Wireless Systems

In this paper an all-optical system exploitable as the core structure for a photonic-based RF transceiver is presented. The proposed scheme is able to simultaneously perform either up- or down-conversion of multiple frequency Ultra-Wide Band (UWB) RF signals, employing a single Mode-Locking Laser (MLL). The system has been experimentally demonstrated and tested by up- and down-converting orthogonal frequency division multiplexing (OFDM) signals over a bandwidth of about 4 GHz. The scheme’s performance has been validated by measuring the error vector magnitude (EVM) of the OFDM signals over the whole considered RF spectrum (from 5 GHz to 26.5 GHz), both in up-conversion and in down-conversion. The measurements show negligible power penalties, lower than 0.5 dB. Since the proposed scheme can act either as an up- or down-converter, and it is composed by easily integratable devices, two identical structures can be combined on a single integrated platform, sharing a single MLL, to build a compact and efficient UWB transceiver.

Photonics-Assisted Multiband RF Transceiver for Wireless Communications

In this paper, the concept of a fully photonics-based multiband radio-frequency transceiver is presented. In the proposed architecture, the precision, wide bandwidth, and flexibility of the photonic technologies allow generating and detecting simultaneous multiple wireless signals in an extremely wide frequency range, up to the millimeter waveband. This approach is therefore promising for future wireless base stations that will need to handle huge data traffic distributed on several different transmission protocols, while minimizing the hardware components. In the proposed system, the capability of easily treating multiple signals simultaneously, and the architecture based on a single pulsed laser for both the transmitter and the receiver sections, permit to reduce the complexity of the transceiver while increasing its functionalities, with a potential benefit in terms of system costs. The paper details the principle of operation of the proposed solution, and describes the implementation of a dual-band wireless transceiver simultaneously working in the X and S bands. The results from the characterization of the transceiver and from its verification in a wireless transmission experiment confirm the potentials of the solution and set the basis for a new paradigm of RF transceivers.

RF Transceiver Based Hand-Motion Crane Control Systems

Human operators have facing many difficulties while driving cranes accurately,and safely because the heavy structure of the crane responds slowly and its payload oscillates.Manipulation difficulty is increased by non-intuitive control interfaces (such as buttons,levers,and joysticks).It needs more experience to master.This paper presents a new model control system that allows operators to drive a crane by simply moving a hand,which is given as the input of the sensor.The output of the sensor will be encrypted and it sends through the RF transmitter.In RF receiver side the signals will be decrypted and the crane will be controlled .H eavy

INTELLIGENT TRAFFIC-SAFETY MIRROR BY USING WIRELESS SENSOR NETWORK

This article is focused on the problematic of traffic safety, dealing with the problem of car intersections with blocked view crossing by a special wireless sensor network (WSN) proposed for the traffic monitoring, concretely for vehicle’s detection at places, where it is necessary. Some ultra-low-power TI products were developed due to this reason: microcontroller MSP430F2232, 868MHz RF transceiver CC1101 and LDO voltage regulator TPS7033. The WSN consist of four network nodes supplied with the special safety lightings which serve the function of intelligent traffic safety mirror.

BER Evaluation of IEEE 802.15.4 Compliant Wireless Sensor Networks Under Various Fading Channels

This paper presents bit error rate (BER) analysis of wireless sensor networks (WSNs) consisting of sensor nodes based on an IEEE 802.15.4 RF transceiver. Closed-form expressions for BER are obtained for WSNs operating over AWGN, Rayleigh and Nakagami-m fading channels. For the purpose of analysis, we consider an IEEE 802.15.4 RF transceiver using direct sequence spread spectrum-offset quadrature phase shift keying (DSSS-OQPSK) modulation under 2.4 GHz frequency band in a WSN. Analytical expressions for BER are derived for a wireless link between sensor nodes that act as a transmitter unit and a base station without considering the effect of interferers in the wireless environment. Numerical results for BER are obtained by varying the IEEE 802.15.4 standard specific physical layer parameters, such as number of bits used to represent a Zigbee symbol, number of modulation levels used in an OQPSK modulator, and various values of Rayleigh and Nakagami-m fading parameters, denoted as $$\alpha $$ ? and $$m$$ m , respectively. Moreover, optimum values of physical layer parameters are identified for improved system performance. It is found that error performance analysis of WSN shows improvement when lower number of bits is used to represent a Zigbee symbol. Specifically, under a Rayleigh fading channel which reflects a real-time WSN environment, the network exhibits better performance only when it is operated at high SNR values, i.e., BER of order $$10^{-2}$$ 10 - 2 is achieved when SNR lies in the range 5---15 dB. Also, the effect of fading parameters on network performance shows that better results are obtained for higher values of $$\alpha $$ ? and $$m$$ m for Rayleigh and Nakagami-m fading channels, respectively.

A Development of Force Distribution Measurement System with High Resolution for Total Knee Arthroplasty

Soft tissue or ligament balancing in total knee arthroplasty is important for ensuring knee joint stability. Correct balancing and appropriate alignment of ligaments extend prosthesis life by preventing unnecessary force fromacting on the prosthesis during routine activities. The current implementation of total knee arthroplasty relies heavily on the subjective “feel” of the surgeon for correct prosthesis implantation onto tibiofemoral components. We developed a force distribution sensing systemto provide quantitative information to surgeons during ligament balancing. The measurement system consists of two main components: two force sensors embedded in trial insert for each condyle and signal acquisition for data processing and force visualization. Sensors were designed and developed using pressure-sensitive conductive rubber that measures changes in resistance in the event of deformation caused by external force. Corresponding voltage measured by circuits is transmitted via an RF transceiver to a computer and visualized as color gradient. Current sensors could measure maximum force of 196.13 N (20 kgf). Results from calibration and experiments on a plastic trial prosthesis indicated that the device has good potential for providing appropriate force distribution information on the knee during total knee arthroplasty procedure.

RF and Microwave Hardware Challenges for Future Radio Spectrum Access

Radio technology for future broadband wireless applications presents a remarkable research opportunity for the RF transceiver and circuit design community. A survey is presented of the low-noise amplifier, frequency conversion, filtering, and transmitter techniques that are being explored for future wireless devices that require wide tuning range, flexible modulation formats, low dc power, and low cost. In all cases, the traditional disadvantages of broadband design approaches can be mitigated by taking advantage of higher levels of integration afforded by CMOS and BiCMOS technologies and improved circuit design approaches.

Design of 4.48–5.89 GHz LC-VCO in 65 nm RF CMOS Technology

This paper describes a 4.48 GHz–5.89 GHz LC voltage-controlled oscillator (LC-VCO) as a key component in RF transceivers. The circuit is fully designed in TSMC’s 65 nm radio-frequency complimentary metal-oxide-semiconductor technology process. The LC-VCO uses the structure of only one couple of NMOS differential negative resistances, tank circuit which consists of an optimal on-chip spiral inductor with switched capacitor and varactor arrays. The proposed design accomplishes wide tuning range frequency by using 6-bit switch capacitor array in addition to linearly varying MOS varactors. A switched current source block is used to improve the performance of the LC-VCO. The oscillator has a wide tuning range, between 4.48 GHz and 5.89 GHz. The LC-VCO dissipates 15.96 mW from a voltage supply of 1.8 V, whereas its phase noise is -124.1 dBc/Hz at 1 MHz offset of a at 5.89 GHz carrier. DOI: http://dx.doi.org/10.5755/j01.eee.20.2.6383