A NOVEL PHASE CONTROL TECHNIQUE FOR INJECTION LOCKED OSCILLATORS

A novel technique to obtain injection locked oscillators phase tuning beyond 180° is demonstrated. The idea is to cascade injection locked oscillators together for phase change accumulation. A two stage injection locked oscillators can theoretically provide a maximum of 360?phase change within the locking range. This is particularly useful for phased array antenna applications.     

New implementation of injection locked technique and its application to low phase noise quadrature oscillators

A new implementation of the injection locked technique is proposed. The incident signal is directly injected into the common-source connection node of the sub-harmonic oscillator instead of the gate of the tail current source, and a narrowband noise filtering network is inserted into the same node to suppress the tail current source noise. A novel quadrature oscillator with the proposed injection locked technique is presented. The simulations show that the phase noise of the quadrature oscillator is about 7 dB better than that of the stand-alone sub-harmonic oscillator. The quadrature oscillator has been implemented in 0.25 um CMOS process and the measured results show that the proposed quadrature oscillator could achieve a phase noise of −130 dBc/Hz at 1 MHz offset from 1.13 GHz carrier while only drawing an 8.0 mA current from the 2.5 V power supply.     

CMOS injection locked oscillators for quadrature generation at radio-frequency

The design of quadrature local oscillators for CMOS wireless transceivers is still one of the most challenging issues. This paper focuses the advantages of injection locking techniques to achieve high-performance quadrature generators. A synchronizing oscillator sets spectral purity while locked oscillators set quadrature accuracy and drive the mixer LO input capacitances. Two different architectures, realized in a 0.18 μm CMOS technology, are illustrated and compared. The first, using LC tank locked oscillators as frequency dividers, is tailored to UMTS and show high driving capability with low power. Simple and accurate equations for the design are reported. The second quadrature generator, employing coupled VCOs driven by an auxiliary VCO, is tailored to DCS1800 and achieves outstanding phase accuracy and phase noise. Experimental results compare favorably against previously published solutions.     

Multiphase sinusoidal oscillators using second generation current conveyors

A voltage-mode Multiphase Sinusoidal Oscillator realized using Second Generation Current Conveyors and only grounded passive elements is introduced in this paper. The proposed topology is suitable for realizing oscillators with both odd and even number of phases without modifying the core of the topology. Only non-inverting Current Conveyors are required for the construction of the oscillator's topology and this is a benefit from the discrete component implementation point of view. The behavior of the proposed topology has been evaluated, through experimental results, in the cases of three and six-phase oscillators.     

First-order allpass filter and sinusoidal oscillators using DDCCs

A voltage-mode first-order allpass filter using one differential difference current conveyor (DDCC), one grounded capacitor and one floating resistor is presented. No passive component matching constraints are required. Because the output impedance of the proposed allpass filter is low, the output terminal can be directly connected to the next stage. Using the proposed first-order allpass filter as a basic building block, a new quadrature oscillator and even-phase sinusoidal oscillators can be obtained. The simulation results confirm the theoretical analysis.     

First CFOA-based explicit-current-output quadrature sinusoidal oscillators using grounded capacitors

To date, no current-feedback operational amplifier (CFOA)-based sinusoidal oscillator has been reported which provides all the following features simultaneously: (i) current-mode quadrature sinusoidal oscillator providing two explicit-current-outputs (ECOs) from high output impedance terminals, (ii) employing no more than three CFOA ICs and six passive components, which include two grounded capacitors, (iii) offers independent tuning of the condition of oscillation (CO) via a resistor and (iv) provides tunability of the ratio of amplitudes of the generated quadrature ECOs via a separate resistor. To the best of authors' knowledge, this article reports first CFOA-based QOs in current-mode (i.e. providing two ECO signals). Experimental results using AD844 CFOA ICs from Analog Devices have been included to verify the workability of the proposed oscillator circuits. An example automatic gain control (AGC) loop to regulate the oscillation amplitude and control the THD has also been used and verified using SPICE simulations using the AD844 macro-model.     

Canonic coupling of sinusoidal oscillators

The problem of coupling between oscillators is usually tackled by employing the Van der Pol equation for representing the oscillators and solving the equations approximately. The present communication suggests another well-known oscillator and simple coupling factors for modeling the system. As a result, the system equations become directly integrable without approximations. The problem of the coupling of two oscillators is solved comprehensively and several regions of distinct dynamic behavior of the system and bifurcation points are identified.     

A theoretical and experimental study of the noise behavior ofsubharmonically injection locked local oscillators

A method for the phase-noise characterization of optically controlled subharmonically injection-locked oscillators that is based on a nonlinear model of synchronized oscillators is presented. It allows FM noise degradation at large-signal levels to be predicted easily and accurately. The theoretical analysis shows that (1) the nth-order subharmonic injection locking oscillator is primarily locked by the nth harmonic output of an injected signal, which is generated by the nonlinearity of the active device; (2) the minimum FM noise degradation factor of the nth-order subharmonically locked oscillator is n² when the injection power is sufficiently strong; and (3) a subharmonic injection locking LO with low injection power, good FM noise degradation, and large locking range can be designed by determining the optimum injection power level, by selecting the optimal nonlinear multiplication factor, and by decreasing the intrinsic noise level of the active device. The experimental results confirm the accuracy of the analysis     

Continuous phase quadrature phase shift keyed signaling techniquewith coding

A continuous phase quadrature phase shift keyed (CPQPSK) modulation technique is presented. This method utilizes a conventional QPSK modulator and a phase trajectory converter to approximate M=4, h=1/4 continuous phase signal and allows low cost, low complexity, and high rate (>1 Gbit/s) CPM modem implementation for bandwidth efficient transmission through nonlinear satellite channels. Using a communications analysis computer program it has been found that CPQPSK has 99 percent out-of-band power of 0.8R (MSK has 99 percent out-of-band power of 1.2 R where R is defined as bit rate), continuous phase trajectories, and nearly constant envelope amplitude. Simulation of realistic hardware designs indicate that the CPQPSK will require an Eb/No of 14 dB to achieve a bit error rate (BER) of 10^-6. Forward error correcting techniques using block codes with an overhead of 10 percent indicate that the Eb/No requirements can be reduced to 11.2 dB for 10^-6 BER     

Estimation of blood perfusion using phase shift in temperatureresponse to sinusoidal heating at the skin surface

A closed form analytical solution of the Pennes' bio-heat equation was obtained for temperature distributions in the skin tissue subject to the sinusoidal heat flux. Phase shifts in the surface temperature response were revealed to be related to local blood perfusion rate and heating frequency. The influence of the thermal contact resistance on the perfusion estimation was investigated. It has been proved that this influence is relatively small because of the phase shift based estimation and can be effectively eliminated by application of highly conductive grease. This analysis provides the theoretical foundation for a new noninvasive modality of blood perfusion estimation based on the surface temperature measurement which can have significant applications in future clinical practices.     

Simple repeater for frequency-modulated signals using transferred-electron oscillators

This letter presents preliminary results obtained from an injection-locked Gunn oscillator operating as an amplifier for frequency-modulated signals.     

Systematic generation of OTA-C sinusoidal oscillators

The authors outline a method for generating all possible, canonic, linearly tunable, OTA-C sinusoidal oscillators systematically.<>     

OTA正弦振荡器的系统综合法研究

根据OTA和零-镜元件的端口约束关系,给出了OTA的8个零-镜描述,以此为基础,利用导纳矩阵扩展法实现了2种不同类型的OTA正弦振荡器:类型Ⅰ使用2个BO-OTA,共有4种不同形式;类型Ⅱ使用3个SO-OTA,共有8种不同形式。由于使用了规范数目的元件,所有电路容易被集成。电路的参数容易被电控调节。计算机仿真结果与理论一致。     

Angle modulation of frequency locked Gunn oscillators

It is shown experimentally and theoretically that frequency modulation through the bias circuit of free-running Gunn oscillators at low modulation frequencies can be converted to an equivalent phase modulation by frequency locking. Judicious choice of locking bandwidth causes the low-frequency phase-modulation coefficient to be of the same order of magnitude as that measured at high modulation frequencies. The phase-modulation coefficient at high frequencies is unaltered by frequency locking.     

Optical phase modulation in an injection locked AlGaAs semiconductor laser

Optical phase modulation by injecting coherent CW light into a directly frequency modulated semiconductor laser is reported. Phase modulation was obtained at up to 800 MHz modulation frequency without distortion for a 1.6 GHz full locking bandwidth. A static phase shift of ? took place with a 0.48 mA bias current change in the injection locked laser. Experimental and theoretical results showed that the product of the normalised phase deviation by the frequency deviation and the cutoff modulation frequency is constant.     

Optical phase modulation in an injection locked AlGaAs semiconductor laser

Optical phase modulation obtained by injecting coherent CW light into a directly frequency-modulated semiconductor laser is reported. Phase modulation at up to a 1 GHz modulation frequency has been obtained without compression for a 1.4 GHz half locking bandwidth. Phase deviation can be represented by the ratio of the original FM deviation to the locking half bandwidth. The phase deviation normalized by the frequency deviation is inversely proportional to the cutoff modulation frequency. A static phase shift of π took place with a 0.48 mA drive current change in the injection locked laser. Reduction in FM noise by means of CW light injection and FM noise accumulation in cascaded injection locked laser amplifiers are discussed, together with the optimum design for an injection locked repeater system.     

A study of steering capability of a microstrip phased array using inter-injection locked oscillators

An innovative, phase coherent, power combining method, known as inter-injection locking applied to linear limited scan phased arrays is investigated. In this novel method, each antenna element in the array is supplied by power from a separate oscillator. However, the oscillator phases are allowed to be synthesized coherently by means of a coupling network and injection currents, being the input controls to the system of coupled phases oscillators. The inter-injection-locked phased arrays studied in this paper provide more design freedom than conventional phased arrays. They also result in systems more adapted to solid state monolithic integration technology.     

扩展二元相移键控调制信号的多路传输

为有效利用信道资源,基于扩展二元相移键控(Extended Binary Phase Shift Keying,EBPSK)调制和解调的独特性,分析了多载波EBPSK调制的传输体制,推导出各路调制信号间参数约束关系,找出传输信号频谱变化规律,提出两种传输方案并设计相应的解调器,实现了多路EBPSK信号的并行传输;针对线谱分布规律修改调制波形,抑制了调制信号功率谱中的线谱杂散;取不同组调制参数进行仿真验证,结果表明两种方案的解调性能趋于一致且与载频间隔有关,载频趋近,系统实现复杂度提高,在相同误码率下解调所需信噪比额外支出约1～2 dB,但传输速率成倍提高,节省了频率资源,表明了这两种方法的可行性、有效性和利用信道资源的合理性.     

Experimental characterisation of avalanche-diode reflection amplifiers and locked oscillators

Qualitative experimental results are presented for a silicon IMPATT diode on the distinction between the undercoupled quenched oscillator, optimised oscillator, locked oscillator, stable amplifier, in relation to the gain, linearity and saturation power. The results are consistent with a nonlinear interpretation of the equivalent diode conductance.     

Predictive digital filtering of sinusoidal signals

The p-step ahead predictive filters for narrowband waveforms with m distinct spectral peaks are considered. By minimization of the noise gain, the coefficients of the optimal Lth order FIR predictor is derived, where L>2m-1. The minimum-length FIR predictor is given by L=2m-1, and the feedback extension of this predictor is studied. Design of feedback gains subject to different optimization criteria is studied in detail. The generalization to complex-valued signals, cascaded predictors, and adaptive predictors are also included. Several design and simulation examples are presented