A digitally controlled constant envelope phase-shift modulator for low-power broad-band wireless applications

A low-power constant envelope phase-shift modulator is presented. The circuit switches the phase of a constant amplitude carrier at output according to the input digital data. Design issues and their impact on the performance of the modulator are discussed. A test chip was fabricated in a 0.18-/spl mu/m CMOS process. Experiment results verified the design principle of the modulator. The modulator consumes 2 mA and is suitable for low-power wireless applications like sensor network and personal area network. Since the circuit is implemented mostly by digital circuit, has broad-band frequency response, and supports high data rate, the modulator can be used at various wireless bands. The measured operating range of carrier frequency is 1.75 to 3.5 GHz, and the modulation data rate can go up to 500 Mb/s. In addition, the modulator can be modified to generate different modulations by digitally controlling both the phase and amplitude of the output signal from a phasor-combining circuit. Therefore, the modulator can potentially be used for software configurable radios.     

A multimode 0.3-200-kb/s transceiver for the 433/868/915-MHz bands in 0.25-/spl mu/m CMOS

A fully integrated transceiver suitable for low-data-rate wireless telemetry and sensor networks operating in the license-free ISM frequency bands at 433, 868, or 915 MHz implemented in 0.25-/spl mu/m CMOS is presented. G/FSK, ASK, and OOK modulation formats are supported at data rates from 0.3 to 200 kb/s. The transceiver's analog building blocks include a low-noise amplifier, mixer, channel filter, received signal-strength indication, frequency synthesizer, voltage-controlled oscillator, and power amplifier. FSK demodulation is implemented using a novel digital complex-frequency correlator that operates over a wide modulation-index range and approximates matched filter detection performance. Automatic gain control, automatic frequency control, and symbol timing recovery loops are included on chip. Operating in the 915-MHz band in FSK mode at 9.6 kb/s, the receiver consumes 19.7 mA from a 3-V supply and achieves a sensitivity of -112.8dBm at 0.1% BER. The transmitter consumes 28.5 mA for an output power of 10 dBm and delivers up to 14 dBm.     

A low power consumption CMOS differential-ring VCO for a wireless sensor

This paper describes a new three-stage voltage controlled ring oscillator (VCO) based on 0.35???m standard CMOS technology. The VCO was designed for a transmitter operating in the 863?C870?MHz European band for wireless sensor applications. The transmitter is designed for binary frequency-shift keying (BFSK) modulation, communicating a maximum data rate of 20?kb/s. In addition to the VCO, the transmitter combines a BFSK modulator, an up conversion mixer, a power amplifier and an 863?C870?MHz band pass filter. The modulator uses the frequency hopping spread spectrum and it is intended for short range wireless applications, such as wireless sensor networks. The oscillation frequency of the VCO is controlled by a voltage V_CTRL. Simulation results of the fully differential VCO with positive feedback show that the estimated power consumption, at desired oscillation frequency and under a supply voltage of 3.3?V, is only 7.48?mW. The proposed VCO exhibits a phase noise lower than ?126?dBc/Hz at 10?MHz offset frequency.     

基于直流光注入直调DFB-LD的可调光毫米波信号产生技术

提出了一种基于直流光注入直接调制分布反馈式半导体激光器(DFB-LD)的载波可调的光毫米波生成方案,利用直接调制DFB-LD的输出瞬态波长随驱动电流增大而蓝移的特点,将直流光注入至直调DFB-LD的0码波长附近注入锁定。锁定的直调激光器在1码时输出的蓝移波长与原注入波长相位相干,再通过光电探测器将拍频信号转换为调制的光毫米波信号。实验重点讨论了40GHz光毫米波的产生,同时完成了30、40、50和60GHz光毫米波的可调谐性实验。本文的方案结构简单,无需外调制器和微波本振,载波可调并可产生高至60GHz光毫米波信号,可作为光/无线混合接入中成本节省的光上变频方案。     

A wideband frequency-shift keying wireless link for inductively powered biomedical implants

A high data-rate frequency-shift keying (FSK) modulation protocol, a wideband inductive link, and three demodulator circuits have been developed with a data-rate-to-carrier-frequency ratio of up to 67%. The primary application of this novel FSK modulation/demodulation technique is to send data to inductively powered wireless biomedical implants at data rates in excess of 1 Mbps, using comparable carrier frequencies. This method can also be used in other applications such as radio-frequency identification tags and contactless smartcards by adding a back telemetry link. The inductive link utilizes a series-parallel inductive-capacitance tank combination on the transmitter side to provide more than 5 MHz of bandwidth. The demodulator circuits detect data bits by directly measuring the duration of each received FSK carrier cycle, as well as derive a constant frequency clock, which is used to sample the data bits. One of the demodulator circuits, digital FSK, occupies 0.29 mm/sup 2/ in the AMI 1.5-/spl mu/m, 2M/2P, standard CMOS process, and consumes 0.38 mW at 5 V. This circuit is simulated up to 4 Mbps, and experimentally tested up to 2.5 Mbps with a bit error rate of 10/sup -5/, while receiving a 5/10-MHz FSK carrier signal. It is also used in a wireless implantable neural microstimulation system.     

Characterization of an optical frequency-shift-keying transmitter based on carrier-suppressed phase modulation

We experimentally characterize an optical frequency-shift-keying transmitter based on optical carrier-suppressed phase modulation. Only one laser source is needed to generate an optical FSK signal. The demonstration of 10-Gb/s FSK signal generation and 50-km transmission verified the improved performance of the proposed transmitter, compared with the previous two-laser schemes. To further reduce the complexity of the transmitter, the phase modulator is omitted and a single MZM modulator is used for both optical carrier-suppression (OCS) and phase modulation. This simplified structure is verified by simulation, implying the feasibility that a FSK transmitter can be constructed with only one laser source and one modulator.     

一种双站后向散射系统结构及其FSK调制和接收

为了实现需要大量无线传感器覆盖和大的通信范围的应用,本文提出了一种双站后向散射系统结构及其基于移频键控(FSK)的非相干调制方案.首先对双站后向散射系统结构的后向散射信号和信道模型进行了详细分析;然后在此基础上针对功率受限情形提出了基于FSK的非相干调制和克服采用双站结构带来的载波频率偏移技术;最后给出基于FSK的接收...     

基于马赫-曾德尔调制器的多种调制格式微波信号的光学生成研究

提出了一种基于马赫-曾德尔调制器(MZM)的 多种调制格式微波信号的光学一体化生成方案。 在本文方案中,微波信号和编码矩形波信号经合路器同时输入到MZM中,通过合理设置编码 信号的幅值使 MZM能够工作在其传输曲线的不同传输点,分别实现了频移键控(FSK)、二进制相移键控(BPSK)和 二倍频BPSK微波信号一体化生成。本文方案仅需要1个MZM而不需要额外加电的或光的选频器 件, 因此具有结构简单、可大范围调谐的优势。特别的,本文方案还可以产生二倍频的BPSK微波 信号,从 而使能够满足更高频的应用需求。在仿真和实验中,分别得到10/20 GHz的FSK、10GHz的BPSK 微波信号,同时产生了20GHz的二倍频BPSK微波信号,有效验证了本 文方案的可行性。     

多种调制格式微波信号的光学产生方案

提出了一种基于偏振调制器（PolM）和Sagnac环级联的多调制格式微波信号的光学产生方案。理论分析了PolM在基带编码信号的驱动下产生偏振键控（PolSK）信号的基本原理,Sagnac环中嵌有两个马赫增德尔调制器（MZM）,分别对顺时针和逆时针传输的PolSK信号进行独立调制。通过合理调整两个MZM的驱动信号,实现了幅移键控（ASK）、频移键控（FSK）和相移键控（PSK）微波信号的产生。在仿真实验中,产生了比特率为2 Gbit/s的40 GHz ASK信号、20/40 GHz FSK信号和20 GHz PSK信号,同时验证了比特率和载波频率的宽带可调谐性。Sagnac环结构提升了系统的稳定性,并且针对每种调制格式的微波信号,在不改变链路结构的情况下其比特率和载波频率都可以通过控制基带编码信号和MZM的射频驱动来进行独立且灵活的调谐。     

A 6.5-GHz energy-efficient BFSK modulator for wireless sensor applications

A 6.5-GHz FSK modulator suitable for low power wireless sensor network is presented. The energy efficient modulator employs closed-loop direct VCO modulation to achieve high data rate, multistage variable loop bandwidth technique for fast startup time and /spl Sigma/-/spl Delta/ for reduced power consumption in the synthesizer with fine resolution in frequency channel selection. The modulator, implemented using 0.25-/spl mu/m CMOS, achieves 20-/spl mu/s startup time with an effective data rate of 2.5 Mb/s while consuming 22 mW.     

FSK Coherent Demodulation Using Second- Harmonic Injection Locked Oscillator

We present an alternative coherent demodulation of frequency shift keying (FSK) signals based on the use of a super harmonic injection locked oscillator (ILO). Demodulation consists of multiplying the incoming FSK signal by the output of the ILO using an up-conversion mixer. The product includes a second harmonic signal that locks the oscillator, closing a non-linear feedback loop, and synchronizes its output with the incoming FSK signal. In addition to the second harmonic, the product also includes a base band signal that reproduces the original modulation. We built and tested a hybrid prototype of the demodulation system for the frequency range from 250 to 300 MHz. The circuit consists of a second-harmonic differential output ILO with varactor diodes as tuning elements and a four quadrant analog multiplier. Our results demonstrate the reliability and robustness of the demodulator system.      

A calibration-less low error two-point modulation transmitter for 802.15.4 application

A low power phase locked loop (PLL) based transmitter for wireless sensor application is presented in this paper. The transmitter adopts two-point modulation architecture in high-pass and low-pass paths of PLL; it modulates the divide ratio through sigma-delta modulator and voltage controlled oscillator (VCO) frequency tuning port simultaneously. An interleave-biased varactor pair is used to linearize the frequency tuning curve of the VCO. Besides, to achieve the desired frequency deviation of 500 kHz, we use a capacitance desensitization technique through combined parallel and serial capacitances with tuning varactors. This topology does not need the minimum size varactor, which is sensitive to process variation and mismatch. Implemented in standard 0.18-μm CMOS process, the transmitter achieves a 5.2 % FSK error for 2 Mbps data rate without using any auto-calibration circuit, consuming 7.8 mW power. Loop filter and crystal are the only off-chip components.     

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.     

A digital approach to an FM exciter

A digital approach to an FM exciter is presented that provides several advantages over previous analog techniques. This approach, called direct digital frequency modulation (DDFM), is centered around a direct digital synthesis (DDS) chip which allows true digital generation of the FM signal. The DDS chip is a perfectly linear modulator with superior phase-noise characteristics over the current analog voltage-controlled oscillator (VCO) approach. The DDS modulator drives a low-noise phase-locked loop (PLL) which allows upconversion to any FM channel without manual tuning. The exciter demonstrates superior microphonics immunity by separating the frequency tuning from the modulation path, thus allowing wider PLL bandwidths. The exciter can accept either the existing composite analog format or can interface with future digital sources     

FSK Modulation Scheme for High-Speed Optical Transmission

In this paper,we describe the generation,detection,and performance of frequency-shift keying (FSK) for high-speed optical transmission and label switching.A non-return-to-zero (NRZ) FSK signal is generated by using two continuous-wave (CW) lasers,one Mach-Zehnder modulator (MZM),and one Mach-Zehnder delay interferometer (MZDI).An RZ-FSK signal is generated by cascading a dual-arm MZM,which is driven by a sinusoidal voltage at half the bit rate.Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating (AWG) demultiplexer with balanced detection.We perform numerical simulation on two types of frequency modulation schemes using MZM or PM,and we determine the effect of frequency tone spacing (FTS) on the generated FSK signal.In the proposed scheme,a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying (DPSK),under varying dispersion management.The performance of an RZ-FSK signal in a 4 × 40 Gb/s WDM transmission system is discussed.We experiment on transparent wavelength conversion based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) and in a highly nonlinear dispersion shifted fiber (HNDSF) for a 40 Gb/s RZ-FSK signal.The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed.We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber (SMF) transmission link with matching dispersion compensating fiber (DCF),under the post-compensation management scheme.Because the frequency modulation format is orthogonal to intensity modulation and vector modulation (polarization shift keying),it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate.It can also be used in orthogonal label-switching as the modulation format for the payload or the label.As an example,we propose a simple orthogonal optical label switching technique based on 40 Gb/s FSK payload and 2.5 Gb/s intensity modulated (IM) label.     

Current Reusing VCO and Divide-by-Two Frequency Divider for Quadrature LO Generation

For low-power and accurate quadrature local oscillator (LO) signal generation, an LC-tank voltage controlled oscillator (VCO) operating at double the required LO-frequency reuses the bias current of divide-by-two frequency divider. The current reusing VCO and divide-by-two frequency divider are targeted to generate the LO signals for a 1.57 GHz global positioning system receiver. Implemented in a 0.18 mum CMOS technology, the current reusing VCO and divide-by-two frequency divider consumes 1.7mA from a 1.8 V supply. The measured phase noise is -120dBc/Hz at 1 MHz offset when the carrier frequency is 1.57GHz.     

35–65-GHz CMOS Broadband Modulator and Demodulator With Sub-Harmonic Pumping for MMW Wireless Gigabit Applications

Sub-harmonic modulator and demodulator are presented in this paper using 0.13-mum standard CMOS technology for millimeter-wave (MMW) wireless gigabit direct-conversion systems. To overcome the main problem of local oscillator (LO) leakage in direct-conversion systems, the sub-harmonically pumped scheme is selected in this mixer design. An embedded four-way quadrature divider is utilized in the sub-harmonic Gilbert-cell design to generate quadrature-phases LO signals at MMW frequency. For broadband applications, a broadband matching design formula is provided in this paper to extend the operational frequency range from 35 to 65 GHz. To improve the flatness of conversion loss at high frequency, high-impedance compensation lines are incorporated between the transconductance stage and LO switching quad of the Gilbert-cell mixer to compensate the parasitic capacitance. The sub-harmonic modulator and demodulator exhibit 6 plusmn1.5 dB and 7.5 plusmn1.5 dB measured conversion loss, respectively, from 35 to 65 GHz. For MMW wireless gigabit applications, the gigabit modulation signal test is successfully performed through the direct-conversion system in this paper. To our knowledge, this is the first demonstration of the MMW CMOS sub-harmonic modulator and demodulator that feature broadband and gigabit applications.     

GaAlAs semiconductor diode laser 4-ary frequency shift key modulation at 100 Mbit/s

4-ary FSK modulation of a semiconductor diode laser by injection current modulation has been demonstrated at a rate of 100 Mbit/s. The injection current modulator has a modular design which allows expansion to M-ary FSK with independent control of each tone frequency. The design allows considerable flexibility in the logical relationship between the source data and the selected frequency tones.     

基于FPGA的小型化微波发射系统设计

针对小型飞行器在飞行过程中工作状态参数的测试需求,设计了一种基于FPGA的小型化宽带零中频微波发射系统。该系统以FPGA为主控单元,接收飞行器上传感器的参数,通过正交上变频模块,实现QPSK调制,完成对所需频段微波信号的输出。经测试,该发射机输出的调制信号频率可达到4 000 MHz,功率可达到10 dBm,各项参数满足设计要求,能够实现数据的高速传输。     

A 1 V Wireless Transceiver for an Ultra-Low-Power SoC for Biotelemetry Applications

This paper presents a 1 V RF transceiver for biotelemetry and wireless body sensor network (WBSN) applications, realized as part of an ultra low power system-on-chip (SoC), the Sensiumtrade. The transceiver utilizes FSK/GFSK modulation at a data rate of 50 kbit/s to provide wireless connectivity between target sensor nodes and a central base-station node in a single-hop star network topology operating in the 862-870 MHz European short-range-device (SRD) and the 902-928 MHz North American Industrial, Scientific & Medical (ISM) frequency bands. Controlled by a proprietary media access controller (MAC) which is hardware implemented on chip, the transceiver operates half-duplex, achieving -102 dBm receiver input sensitivity (for 1E-3 raw bit error rate) and up to -7 dBm transmitter output power through a single antenna port. It consumes 2.1 mA during receive and up to 2.6 mA during transmit from a 0.9 to 1.5 V supply. It is fabricated in a 0.13 mum CMOS technology and occupies 7 mm² in a SoC die size of 4 times 4 mm².