射频与基带参考时钟不同源对GPS载波相位平滑伪距定位的影响

无论GPS接收机的射频和基带参考时钟是否同源,都不会影响伪距定位。然而,对于载波相位平滑伪距定位,本文的理论分析表明:在新增卫星时,射频和基带参考时钟不同源将使新增星和原有星的平滑伪距钟差产生偏差,进而导致大幅度定位误差。在时钟同源和不同源两种条件下,利用自研的GPS基带芯片“航芯2E”,开展了大量硬件实验,验证了理论分析的正确性。论文得出的载波相位平滑伪距定位的接收机其射频和基带参考时钟必须同源的结论,对于GPS射频和基带芯片的模块化、系列化的规划和设计具有指导意义。      

Determination of Equivalent Circuit Parameters Describing Noise from a Gunn Oscillator

The AM and FM fluctuations in an oscillator output are originated from impedance fluctuation in low frequencies (baseband noise) and voltage or current fluctuation in the vicinity of the carrier frequency (RF noise). In this paper, from newly defined "complex correlation coefficient between AM and FM noises," contributions of baseband and RF noises to the AM and FM noises are determined. Examples of data for X-band Gunn oscillators show that both the AM and FM noises are mainly caused by the baseband noise in the vicinity of the carrier frequency (within 1-kHz band), whereas they are mainly due to the RF noise at frequencies further than 10 kHz from the carrier frequency.     

Analysis of noise up-conversion in microwave field-effecttransistor oscillators

The conversion process of the low frequency noise into phase noise in field-effect transistors (FET) oscillators is investigated. First, an evaluation of the baseband noise contribution to the oscillator phase noise is provided from the analysis of the baseband noise and the frequency noise spectra. A distinction is made within the different components of the low frequency noise contributions to close-in carrier phase noise. Next, the frequency noise of the oscillator circuit is analyzed in terms of the FET's low frequency noise multiplied by the oscillator's pushing factor. Though this product usually provides a good evaluation of the phase noise, experimental results presented here show the inaccuracy of this method at particular gate bias voltages where the pushing factor decreases to zero. To account for these observations, a new nonlinear FET model involving at least two noise sources distributed along the channel is proposed     

Isolated locked hybrid junction power combiner

The isolated locked hybrid junction power combiner, consisting of a single hybrid junction, appropriate phase-shifting element and circulator, combines three 1-port oscillators (one master oscillator strongly locking the other oscillators). Combiner frequency, noise and locking properties are controlled by the master oscillator, and combining efficiency close to 100%, can be achieved. The combiner can be extended in a modular fashion.     

MOS环振式数字加速度传感器

提出了一种新的环振式数字加速度传感器,它采用做在硅梁上的MOS环形振荡器作为敏感元件,两个反方向变化的环振输出信号通过集成在片内的混频器实现频率相减.该传感器具有准数字输出、灵敏度高、温度系数低以及制作工艺简单等特点.分析了环形振荡器的频率特性,以及环形振荡器的谐振频率和加速度的关系,分析并设计了加速度传感器的环形振荡器电路、混频器电路、物理结构以及制作工艺,并制作了样品,其灵敏度为6 .91k Hz/g.     

The Effect of Mismatches and Delay on the Quadrature Error of a Cross-Coupled Relaxation Oscillator

Cross-coupled relaxation oscillators can produce two highly accurate quadrature output signals (Verhoeven, 1992). We present a high-level model of these oscillators in terms of circuit parameters, from which we obtain explicit equations for duty-cycle, oscillation frequency, and quadrature error. They show the influence on the oscillator performance of component mismatches and other nonideal effects, such as delays. The results provide useful guidelines for the design of high performance oscillators. The theoretical results are confirmed by simulation and by measurements on a test chip.     

Nonlinear dynamics of shape memory alloy oscillators in tuning structural vibration frequencies

Shape memory alloy (SMA) is one of the novel advanced functional materials that has an increasing range of current and potential applications, including smart materials and structures, bio-medical and nanotechnologies. This range includes also applications of SMA for control and vibration tuning of various structures, seismic response mitigation, and others. In vibration tuning in many of these applications, it is often necessary to apply supplementary oscillators to absorb the vibration energy input into the primary system. Moreover, when supplementary oscillators are used in these applications, we often have to deal with a situation where the primary vibration frequency is not known a priori. In such cases, we have to design a robust supplementary oscillator such that it is able to operate in a rather wide range of frequencies. A SMA-based oscillator is an ideal candidate for these purposes. In the present paper, we propose a dynamic nonlinear model and its numerical realization for using SMA oscillators as vibration absorbers. The system under consideration consists of a SMA rod and an end-mass. We demonstrate that due to the thermo-mechanical coupling, the vibration characteristics of the supplementary oscillator can be tuned by changing its temperature. The dynamic nonlinear model of the SMA oscillator is simplified for the vibration analysis and an efficient numerical methodology is proposed to evaluate the performance of the oscillator. It is demonstrated that the vibration of the primary system can be tuned within a rather wide frequency range by using the SMA oscillator. It is also shown that at high temperatures the performance of the oscillator is close to that of a linear oscillator, while at low temperatures, the SMA oscillator behaves as a regular damper by using its dissipation due to mechanically-induced phase transformations.     

A Microwave Frequency Standard Employing Optically Pumped Sodium Vapor

An instrument in which a simple microwave triode oscillator is stabilized by reference to a natural atomic resonance---the field-independent hyperfine resonance of sodium---is described. Light from a sodium lamp is transmitted through an absorption cell containing sodium vapor and argon, which is placed in a resonant cavity. This light produces population differences between the two quantum levels which are involved in the desired atomic resonance and provides a means of detecting resonance, The cavity is excited by an external microwave triode oscillator which is frequency modulated to a small degree at 60 cycles. When the exciting oscillator frequency coincides with the center of the atomic resonance line, the signal observed by a photocell will be a modulation of the transmitted light at 120 cycles and higher even-order harmonics. Any deviation from line center will introduce a 60-cycle component whose phase and magnitude may be detected to produce an error signal to retune the oscillator in the usual servo loop manner. Theory predicts that an accuracy of possibly one part in 10/sup 10/ can be achieved by systems using sodium and suitable local oscillators. It is evident also that such systems can be engineered into quite small packages, making possible many new applications of microwave oscillators stabilized to high order.     

A Beam-Steering Antenna Array Using Injection Locked Coupled Oscillators With Self-Tuning of Oscillator Free-Running Frequencies

The analysis and experimental results of an antenna array using injection locked coupled oscillators with self-tuning of oscillator free-running frequencies are presented. With the use of coupled type-II phase locked loops for tuning oscillator free-running frequencies and an external injection signal for stabilizing the array operating frequency, this antenna array can steer its beam through a single control voltage and hold its output frequency at the injection signal frequency in operation. In addition, its beam-pointing error arising from phase errors in coupled oscillators can be reduced and the array works well over a certain frequency band. Phase dynamics and stability are studied and experimentally verified. Experimental results of a three-element injection locked coupled oscillator array show that its uniform phase progression ranges between $-$16 $^{circ}$ and 52$^{circ}$ , and the phase errors are less than 5 $^{circ}$ at 2.7 GHz. The operation bandwidth is shown from 2.68–2.72 GHz. By loading the injection locked coupled oscillator array with rectangular patch antennas, the beam-steering radiation characteristics are measured at various control voltages.      

A single-chip quad-band (850/900/1800/1900 MHz) direct conversion GSM/GPRS RF transceiver with integrated VCOs and fractional-n synthesizer

Recent trends in the integration of entire systems on-chip have spurred the development of homodyne radios as alternatives to the more mature yet harder to integrate superheterodyne architectures. This paper presents a monolithic device that integrates all of the functions necessary to implement a multiband homodyne global system for mobile telecommunications (GSM) radio except for the power amplifier (PA) and radio frequency (RF) passives. The single BiCMOS chip includes a quad-band direct conversion receiver that down converts RF to quadrature analog baseband. The front-end circuitry is followed by a low-DC-offset, high-dynamic-range, analog I/Q baseband chain. The transmit section is comprised of a quad-band up-conversion transmit phase-locked loop (PLL) including on chip transmit voltage-controlled oscillators (VCOs). The stringent GSM receive band phase noise specifications are met without the use of surface acoustic wave filters. A single /spl Sigma//spl Delta/ fractional-N synthesizer locking a fully integrated ultrahigh frequency VCO generates the system local oscillator signal.     

Stable and efficient lattice algorithms for adaptive IIR filtering

Previous attempts at applying lattice structures to adaptive infinite-impulse-response (IIR) filtering have met with gradient computations of O(N²) complexity. To overcome this computational burden, two new lattice-based algorithms are proposed for adaptive IIR filtering and system identification, with both algorithms of O(N) complexity. The first algorithm is a reinterpretation of the Steiglitz-McBride method (1965), while the second is a variation on the output error method. State space models are employed to make the derivations transparent, and the methods can be extended to other parameterizations if desired. The set of possible stationary points of the algorithms is shown to be consistent with the convergent points obtained from the direct-form versions of the Steiglitz-McBride and output error methods, whose properties are well studied. The derived algorithms are as computationally efficient as existing direct-form based algorithms, while overcoming the stability problems associated with time-varying direct-form filters     

以混频器作为信号处理单􀀂 元的环振式压力传感器

提出了一种新的环振式数字压力传感器，它采用做在硅梁上的MOS环形振荡器作为敏感元件，两个反方向变化的环形振荡器的输出信号通过集成在片内的混频器实现频率相减，分析了环形振荡器的频率特性，以及环形振荡器的谐振频率和压力的关系，分析并设计了压力传感器的环形振荡器电路、混频器电路、物理结构以及制作工艺，并制作了样品，其灵敏度为1．52kHz／kPa。     

Surface-acoustic-wave delay-line controlled low-frequency oscillators

Surface-acoustic-wave delay line is used as the frequency controling element of a low-frequency oscillator, operating at a fundamental frequency of a few kilohertz. Some salient properties of such oscillators are discussed. Initial experimental results indicate that high-frequency stability can be obtained.     

Improved memristor-based relaxation oscillator

This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is discussed and validated by the PSPICE circuit simulations showing an excellent agreement. MATLAB results are also introduced to demonstrate the resistance range and the corresponding frequency range which can be obtained from the proposed relaxation oscillator.     

Experimental Evaluation of Noise Parameters in Gunn and Avalanche Oscillators

Equations are presented that express noise-to-carrier ratio and rms frequency deviation of a negative-resistance oscillator with a multiple-resonant circuit in terms of effective available noise power densities of both 1/f and white-noise sources, an effective saturation factor, and an appropriate Q/sub L/ of the oscillator. Experimental evaluation of the noise parameters in Gunn and avalanche oscillators by use of these equations is described. AM and FM noise measurements have been made on X-band Gunn oscillators and Si and GaAs avalanche oscillators for frequency off carriers extending from 1 kHz to 10 MHz. Both 1/f and white noise have been observed in these oscillators. The validity of the above equations has been verified for Gunn oscillators from the dependence of the noise spectra on Q/sub L/. For Gunn oscillators and Si and GaAs avalanche oscillators, the effective noise-temperature ratio for white noise, N/kT/sub 0/, has been found to be 23~29, 41~51, and 38~44 dB, and the effective saturation factor to be 2~2.9, 0.5~2.4, and 2, respectively. An increase of N/kT/sub 0/ with the RF voltage across the diode has been observed in Si avalanche oscillators. Parameters for 1/f noise have also been evaluated approximately.     

An AGC Circuit Design for a Variable-Frequency Sinusoidal Oscillator with Wide Frequency Range and Low Distortion Level

An up-down counter, multiplier, digital-to-analog (D/A) converter, and high-speed comparators are employed to achieve an automatic gain control (AGC) circuit, which corrects the pair of characteristic roots of the overall system automatically to the imaginary axis of the complex frequency plane. A negative feedback technique with digital hardware is applied on the loop gain control. No lowpass filter is needed to detect the oscillation amplitude. Thus, this technique is suitable for sinusoidal oscillators with a wide oscillation frequency range. Wien-bridge and phase-shift oscillators with an oscillation frequency range from 17 Hz to 1 MHz are tested with the proposed AGC circuit. The total harmonic distortions of the Wien-bridge sinusoidal oscillator with the proposed AGC circuit are verified to be very small. An application to a variable-frequency sinusoidal oscillator is also described. The experimental results demonstrate the static characteristics and dynamic responses of the overall system.     

A cross-coupled-structure-based temperature sensor with reduced process variation sensitivity

An innovative,thermally-insensitive phenomenon of cascaded cross-coupled structures is found.And a novel CMOS temperature sensor based on a cross-coupled structure is proposed.This sensor consists of two different ring oscillators.The first ring oscillator generates pulses that have a period,changing linearly with temperature.Instead of using the system clock like in traditional sensors,the second oscillator utilizes a cascaded cross-coupled structure to generate temperature independent pulses to capture the result from the first oscillator.Due to the compensation between the two ring oscillators,errors caused by supply voltage variations and systematic process variations are reduced.The layout design of the sensor is based on the TSMC13G process standard cell library.Only three inverters are modified for proper channel width tuning without any other custom design.This allows for an easy integration of the sensor into cell-based chips.Post-layout simulations results show that an error lower than±1.1℃ can be achieved in the full temperature range from-40 to 120℃.As shown by SPICE simulations,the thermal insensitivity of the cross-coupled inverters can be realized for various TSMC technologies:0.25/μm,0.18μm,0.13μm,and 65 nm.     

Linewidth measurements and phase locking of Josephson oscillatorsusing RSFQ circuits

We present a technique for linewidth measurement and phase-locking of Josephson oscillators using digital rapid single-flux-quantum (RSFQ) circuits. The oscillator consists of a resistively shunted 6 μm×6 μm Nb/AlO_x/Nb Josephson tunnel junction that is integrated with RSFQ input and output circuits. A cascade of RSFQ T flip-flops is used to directly monitor the output of the Josephson oscillator. Spectral characteristics have been measured directly for oscillator frequencies ranging from 10-50 GHz. The linewidth can be reduced by over 100 times by phase-locking the oscillator to an RSFQ pulse train generated by an external sinusoidal signal. These Josephson oscillators can be used as on-chip stable high frequency clocks for RSFQ circuits     

RC oscillators with oscillation frequency independent of the op.-amp. gain-bandwidth product

Applying the determining equation proposed by Chua and Tang (1982), a frequency sensitivity problem in RC op.-amp. based oscillators is considered. A new expression for the sensitivity of oscillation frequency, ω_o, to changes in any oscillator parameter is developed. Then, the condition for this frequency to be insensitive to changes in the gain-bandwidth products (GB) of the op.-amp. used in the oscillator is formulated. Examples of two circuits exhibiting a zero sensitivity of ω_o to the GB changes (a very desirable feature) are presented. The first example represents oscillators with a single op.-amp. whose slew-rate effect is the only oscillator non-linearity. The second example concerns oscillators with a so-called composite amplifier where non-linear elements included in the oscillator feedback network are responsible for amplitude stabilization.     

Phase-locked millimeter-wave two-port second-harmonic Gunnoscillators

Two-port harmonic oscillators have been developed which are suitable for voltage-controlled-oscillator (VCO) operation in frequency stabilized systems. Two oscillator designs are presented. The first has a fundamental frequency cavity located above the harmonic output cavity and the fundamental is coupled by means of the Gunn device bias-line filter. The second design is an in-line structure which uses a waveguide taper as the filter element separating the fundamental and harmonic frequency components. The latter design is a translation of the first oscillator concept onto a single plane, so that the prospect of an integrated monolithic version is conceivable. The performance of the oscillators is discussed, and a demonstration of their use in a heterodyne phase-locked loop control system is presented