Novel Ultra-Low-Power Class AB CCII+ Based on Floating-Gate Folded Cascode OTA

In this paper, a novel low-voltage ultra-low-power class AB current conveyor of the second generation based on folded cascode operational transconductance amplifier OTA with floating-gate differential pairs is presented. The main features of the proposed conveyor are design simplicity and rail-to-rail input voltage range at a low supply voltage of ±0.5 V. The proposed conveyor has a reduced power consumption of only 10 μW. Due to these features, the proposed conveyor could be successfully employed in a wide range of low-voltage low-power analog signal processing applications. PSpice simulation results using the 0.18 μm CMOS technology from TSMC are included to prove the results. As an example of application, a current-mode quadrature oscillator is designed and its functionality is proved by simulation.     

A low-voltage low-power CMOS transmitter front-end using current mode approach for 2.4 GHz wireless communications

This paper presents a low-voltage low-power transmitter front-end using current mode approach for 2.4 GHz wireless communication applications, which is fabricated in a chartered 0.18 μm CMOS technology. The direct up-conversion is implemented with a current mode mixer employing a novel input driver stage, which can significantly improve the linearity and consume a small amount of DC current. The driver amplifier utilizes a transimpedance amplifier as the first stage and employs an inter-stage capacitive cross-coupling technique, which enhances the power conversion gain as well as high linearity. The measured results show that at 2.4 GHz, the transmitter front-end provides 15.5 dB of power conversion gain, output P?1 dB of 3 dBm, and the output-referred third-order intercept point (OIP3) of 13.8 dBm, while drawing only 6 mA from the transmitter front-end under a supply voltage of 1.2 V. The chip area including the testing pads is only 0.9 mm×1.1 mm.     

Ultra-Wideband, Low-Power, Inductorless, 3.1�C4.8?GHz, CMOS VCO

A low-power, inductorless, UWB CMOS voltage controlled oscillator is designed in 0.18 μm CMOS technology targeting to a UWBFM transmitter application. The VCO is a Double-Cross-Coupled Multivibrator and generates output frequencies ranging from 1.55 GHz to 2.4 GHz. A low-power frequency doubler based on a Gilbert cell, which operates in weak inversion, doubles the VCO tuning range from 3.1 GHz to 4.8 GHz. The proportionality between the oscillation frequency and the bias current is avoided in this case for the entire achieved tuning range resulting in a low-power design. The selected architecture provides high suppression, over 45 dB, for the 1^st and 3^rd harmonics, while enabling high-frequency operation and conversion gain due to the unbalanced structure and the single-ended output. The proposed VCO draws 4 mA from a 1.8 V supply, it has a phase noise of −76.7 dBc/Hz at 1 MHz offset from the center frequency, while it exhibits a very high ratio of tuning range (43%) over power consumption equal to 7.76 dB.     

A low-power,wide-range variable gain CMOS RF transmitter for 900 MHz wireless communications

This paper presents a low-power, wide-range variable gain RF transmitter for 900 MHz-band wireless communication applications based on a standard 0.18 μm CMOS technology. A very wide-range variable gain and high linearity up-conversion mixer is obtained by using a newly transconductance stage. High linearity at low power dissipation driver amplifier can be obtained by adopting a folded cascode topology with an additional gate-source capacitor. The measured results show conversion gain of 16 dB, dB-linear gain variation of 47 dB with the linearity error less than ±0.5 dB, output P-1 dB of 2 dBm, and OIP3 of 12 dBm while dissipating 4 mA from 1.25 V supply.     

High-Precision Differential-Input Buffered and External Transconductance Amplifier for Low-Voltage Low-Power Applications

Recently, the demand for low-voltage low-power integrated circuits design has grown dramatically. For battery-operated devices both the supply voltage and the power consumption have to be lowered in order to prolong the battery life. This paper presents an attractive approach to designing a low-voltage low-power high-precision differential-input buffered and external transconductance amplifier, DBeTA, based on the bulk-driven technique. The proposed DBeTA possesses rail-to-rail voltage swing capability at a low supply voltage of ±400 mV and consumes merely 62 μW. The proposed circuit is a universal active element that offers more freedom during the design of current-, voltage-, or mixed-mode applications. The proposed circuit is particularly interesting for biomedical applications requiring low-voltage low-power operation capability where the processing signal frequency is limited to a few kilohertz. An oscillator circuit employing a minimum number of active and passive components has been described in this paper as one of many possible applications. The circuit contains only a single active element DBeTA, two capacitors, and one resistor, which is very attractive for integrated circuit implementation. PSpice simulation results using the 0.18 μm CMOS technology from TSMC are included to prove the unique results.     

An Ultra-Low-Power Injection Locked Transmitter for Wireless Sensor Networks

This paper presents the principles for designing low-power transmitters for wireless sensor networks. Based on these principles, an injection-locked transmitter is implemented in a standard 0.13-$muhbox m$CMOS process and packaged using chip-on-board assembly. The transmitter utilizes a film bulk acoustic resonator (FBAR) to obtain a stable carrier at 1.9 GHz. At 0 dBm output power, the transmitter achieves an efficiency of 32% at 50 kb/s and 28% at 156 kb/s. With 50% on-off keying, the transmitter consumes 1.6 and 1.8 mW, respectively.     

A low-voltage low-power programmable fractional PLL in 0.18-μm CMOS process

The prolific growth of portable electronic devices (PED) has generated tremendous interests among researchers to develop programmable phase-locked loops (PLLs) because of their abilities to produce multiple spectrally pure output frequencies from a fixed frequency oscillator. The power consumption of the RF block of a PED is mostly dominated by the programmable PLLs which are widely used in the design of these devices. Therefore to reduce the overall power consumption in a portable device and to increase the battery life time, low-voltage and low-power are the two key requirements for the PLL design. In this work an improved programmable fractional frequency divider has been incorporated to enhance the overall performance of the PLL that includes lower operating supply voltage and lower power consumption compared to the state-of-art. The proposed programmable fractional PLL has an operating frequency in the range of 1.7–2.5 GHz, and a frequency resolution of 2.5 MHz. Measurement results reveal that the proposed programmable PLL can operate at 2.4 GHz with a 1.46 V power supply voltage and only 10 mW of power consumption.     

A Low-Power Encoder For Pyramid Vector Quantization of Subband Coefficients

A real-time, low-power video encoder design for pyramid vector quantization (PVQ) has been presented. The quantizer is estimated to dissipate only 2.1 mW for real-time video compression of images of 256 × 256 pixels at 30 frames per second in standard 0.8-micronCMOS technology with a 1.5 V supply. Applying this quantizer to subband decomposed images, the quantizer performs better than JPEG on average. We achieve this high level of power efficiency with image quality exceeding that of variable rate codes through algorithmic and architectural reformulation. The PVQ encoder is well-suited for wireless, portable communication applications.     

Low-Power Analog Integrated Circuits for Wireless ECG Acquisition Systems

This paper presents low-power analog ICs for wireless ECG acquisition systems. Considering the power-efficient communication in the body sensor network, the required low-power analog ICs are developed for a healthcare system through miniaturization and system integration. To acquire the ECG signal, a low-power analog front-end system, including an ECG signal acquisition board, an on-chip low-pass filter, and an on-chip successive-approximation analog-to-digital converter for portable ECG detection devices is presented. A quadrature CMOS voltage-controlled oscillator and a 2.4 GHz direct-conversion transmitter with a power amplifier and upconversion mixer are also developed to transmit the ECG signal through wireless communication. In the receiver, a 2.4 GHz fully integrated CMOS RF front end with a low-noise amplifier, differential power splitter, and quadrature mixer based on current-reused folded architecture is proposed. The circuits have been implemented to meet the specifications of the IEEE 802.15.4 2.4 GHz standard. The low-power ICs of the wireless ECG acquisition systems have been fabricated using a 0.18 μm Taiwan Semiconductor Manufacturing Company (TSMC) CMOS standard process. The measured results on the human body reveal that ECG signals can be acquired effectively by the proposed low-power analog front-end ICs.     

Low-power/low-voltage RF microsystems for wireless sensors networks

This paper presents radio-frequency (RF) microsystems (MSTs) composed by low-power devices for use in wireless sensors networks (WSNs). The RF CMOS transceiver is the main electronic system and its power consumption is a critical issue. Two RF CMOS transceivers with low-power and low-voltage supply were fabricated to operate in the 2.4 and 5.7 GHz ISM bands. The measurements made in the RF CMOS transceiver at 2.4 GHz, which showed a sensitivity of −60 dBm with a power consumption of 6.3 mW from 1.8 V supply. The measurements also showed that the transmitter delivers an output power of 0 dBm with a power consumption of 11.2 mW. The RF CMOS transceiver at 5.7 GHz has a total power consumption of 23 mW. The target application of these RF CMOS transceivers is for MSTs integration and for use as low-power nodes in WSNs to work during large periods of time without human operation, management and maintenance. These RF CMOS transceivers are also suitable for integration in thermoelectric energy scavenging MSTs.     

A Survey of Energy Efficient Network Protocols for Wireless Networks

Wireless networking has witnessed an explosion of interest from consumers in recent years for its applications in mobile and personal communications. As wireless networks become an integral component of the modern communication infrastructure, energy efficiency will be an important design consideration due to the limited battery life of mobile terminals. Power conservation techniques are commonly used in the hardware design of such systems. Since the network interface is a significant consumer of power, considerable research has been devoted to low-power design of the entire network protocol stack of wireless networks in an effort to enhance energy efficiency. This paper presents a comprehensive summary of recent work addressing energy efficient and low-power design within all layers of the wireless network protocol stack.     

A novel high-efficiency linear transmitter using injection-locked pulsed oscillator

This letter presents a novel high-efficiency linear transmitter using pulse-width modulation (PWM). An envelope of radio frequency (RF) input signal is modulated by the PWM. The modulated signal is applied to the gate bias of a class F injection-locked power oscillator and switches it on and off. By filtering the pulsed oscillating output signal of the injection-locked oscillator using high-Q bandpass filter, the input signal is restored. This technique enables the transmitter to have high efficiency with good linearity. Also, there is little distortion near saturation point of an active device. The measured results show efficiency of 54.6% and very good linearity in PCS band at 26.4-dBm output power.     

Optimal transmission frequency for ultralow-power short-range radio links

Analysis determining the optimal transmission frequency for maximum power transfer across a short-range wireless link is introduced, including a comparison of near-field transmission with far-field transmission. A new near-field power transfer formula has been derived, which allows direct comparison with the well-known far-field Friis transmission formula. Operating charts are presented, which provide the designer with the preferred transmission frequency as a function of distance and antenna dimensions, together with surface plots which show the power transfer for this frequency. The analysis, performed for loop antennas, has been used to evaluate the oscillator transmitter as a low-power topology. It is shown that the requirement of a high-Q factor to realize a low-power oscillator need not be contradictory to achieving optimal far-field radiation characteristics. Based on this fact an approach to sizing loop antennas for low-power oscillator transmitters is suggested.     

A 0.8-V 816-nW delta–sigma modulator for low-power biomedical applications

This letter discusses the implementation of a low-voltage, low-power delta–sigma modulator as a sensing stage for biomedical applications. A distributed feed-forward structure and bulk-driven operational transconductance amplifier are used in order to achieve efficient operation at a supply voltage of 0.8 V. Instead of conventional low-voltage amplifier architectures, our design uses folded-cascode amplifiers, although they are not used in most low-voltage circuits. A wide input swing is achieved by using the bulk-driven approach, and the drawback of the limited voltage swing of the cascoded output stage is overcome by the distributed feed-forward modulator. The designed modulator has a dynamic range of 49 dB at a 0.8-V supply voltage and consumes only 816 nW of power for the 250-Hz bandwidth. The core chip size of the modulator is 1000 μm × 500 μm by using the 0.18-μm standard CMOS process.     

Integrated electrically tuned X-band power amplifier utilizing Gunn and IMPATT diodes

A totally integrated X-band power amplifier for FM and PM communication system applications having 1-W output power and 30-dB gain is described. The amplifier consists of two electrically tuned injection-locked oscillator stages taht are tunable over a 500-MHz range with 250-MHz minimum locking bandwidth. A Gunn diode is utilized in the first stage and a silicon IMPATT diode in the second stage oscillator for the best overall FM noise, AM/PM conversion, output power, and efficiency. The FM noise and AM/PM conversion of the separate stages are presented in relation to overall amplifier performance. The amplifier design includes a combined power monitor and `out-of-lock' detection circuit. In addition, temperature-compensated current and voltage regulators and automatic interface circuitry to shut off the amplifier when out of lock occurs are described. Temperature compensation for the free-running frequency of each stage over the temperature and frequency range is discussed.     

Portable video-on-demand in wireless communication

Our present ability to work with video has been confined to a wired environment, requiring both the video encoder and decoder to be physically connected to a power supply and a wired communication link. This paper describes an integrated approach to the design of a portable video-on-demand system capable of delivering high-quality image and video data in a wireless communication environment. The discussion will focus on both the algorithm and circuit design techniques developed for implementing a low-power video compression/decompression system at power levels that are two orders of magnitude below existing solutions. This low-power video compression system not only provides a compression efficiency similar to industry standards, but also maintains a high degree of error tolerance to guard against transmission errors often encountered in wireless communication. The required power reduction can best be attained through reformulating compression algorithms for energy conservation. We developed an intra-frame compression algorithm that requires minimal computation energy in its hardware implementations     

A CMOS low-voltage low-power temperature sensor

Temperature sensing circuits are used in a wide range of applications such as in the biomedical area, cold chain monitoring and industrial applications. In the biomedical area, temperature patient monitoring systems can be found in a wide range of hospital applications such as the intensive care unit, surgery rooms and clinical analysis. When the systems also incorporate also communication features, they form a telemedicine system in which the patients can be remotely monitored. The need of portability promotes a demand for sensors and signal conditioners that can be placed directly on the patient or even implanted. Implanted systems provide comfort for the patient during the physiologic data acquisition. These systems should operate preferably without a battery, in which the energy is obtained by inductive coupling (RF link). Implanted devices require low-voltage and low-power operation in a small silicon area in order to offer safety to the patient, mainly in terms of excessive exposure to RF. This work presents a low-voltage low-power temperature sensor, suitable for implanted devices. The circuit topology is based on the composite transistors operating in weak inversion, requiring extremely low current, at low-voltage (0.8 V), with just 100 nW power dissipation. The circuit is very simple and its implementation requires a small silicon area (0.062 mm²). The tests conducted in the prototypes validate the circuit operation.     

Wireless smart sensor with small spiral antenna on Si-substrate

This paper presents a wireless smart sensor (WSS) with a thermoelectric sensor, a wireless transmitter and a small spiral antenna on a single package. To transmit a sensor signal, the wireless transmitter was designed to consist of an amplifier, a modulator, an oscillator, a buffer stage and an antenna. The wireless transmitter used dual pulse position modulation for low-power transmission. The fabricated transmitter has a sampling frequency of 2.6 kHz and an output carrier wave frequency of 300 MHz band due to the higher far field radiation of the transmitted signals from inside the body. The small size spiral antenna on the chip was fabricated for the transmission of carrier waves. The antenna has a bandwidth of 270-360 MHz for VSWR<2 and a gain of −40 dBi. The fabricated sensor, transmitter and spiral antenna were packaged with bond-wire on a single package. The WSS consumed a power of about 16.9 mW at the supply power of 5 V. The electric field strength of the WSS was measured to be 64.6 dB μV/m at a distance of 3 m. The wireless operation of the fabricated WSS was confirmed by demonstrating that the sensor signal was modulated by the transmitter and that the modulated sensor data was transmitted through the small size spiral antenna.     

Ultra wideband, low-power, 3-5.6 GHz, CMOS voltage-controlled oscillator

In this paper, a low-power inductorless ultra wideband (UWB) CMOS voltage-controlled oscillator is designed in TSMC 0.18 μm CMOS technology as a part of a ultra wideband FM (UWBFM) transmitter. The VCO includes a current-controlled oscillator (CCO) which generates output frequencies between 1.5 and 2.8 GHz and a voltage-to-current (V-to-I) converter. A low-power frequency doubler based on a Gilbert cell, which operates in weak inversion, doubles the VCO tuning range achieving oscillation frequencies between 3 and 5.6 GHz. Thus, the well-known proportionality between the oscillation frequency and the bias tuning current in CCOs is avoided for the entire achieved tuning range, resulting in a lower power design. The employed architecture provides high suppression, over 45 dB, of the 1st and 3rd harmonics, while enabling high-frequency operation and conversion gain due to the unbalanced structure and the single-ended output. The current consumption is 5 mA at a supply voltage of 1.8 V. The VCO exhibits a phase noise of −80.56 dBc/Hz at 1 MHz frequency offset from the carrier and a very high ratio of tuning range (60.4%) over power consumption equal to 8.26 dB which is essential for a UWBFM transmitter.     

基于低压电力线传输网的无线光通信研究

介绍一种低压电力线传输网与无线红外传输相结合的通信机制,分析了调制方式、信号耦合方式和阻抗匹配以及影响信号传输的因素,给出了增强带负载能力和消除电力线负载效应的解决方法。实验表明,选择合适的调制方式与载波频率可降低电力线信道噪声的影响,实现了低压电力线与大气信道视距内信号稳定可靠传输,为短距离无线光通信提供一种新方法。