低插入损耗的8-18 GHz CMOS无源延时线设计

针对采用级联延时结构的高频延时线存在损耗较高的问题,提出了一种采用0.18 μm CMOS工艺的宽带延时线集成电路芯片,其性能指标为5 bit延时控制,120 ps最大延时,3.9 ps延时分辨率。该延时电路采用二阶全通网络(all pass networks,APN)作为延时结构,并设计了一种新的群延时交错方法。该方法利用二阶APN群延时频率响应的峰值特性,从单个APN电路中提取更多的群延时,可以用较少的无源二阶APN电路实现更高的群延时,同时又能降低所设计延时线的插入损耗。采用0.18 μm CMOS工艺进行了具体实现和性能测试。结果表明,该电路芯片面积为1.2×2.7 mm2,与现有集成延时线相比,所提电路的插入损耗更低。在8~18 GHz的频率范围内,插入损耗为12.6~20.5dB,均方根延时误差小于3.3ps。     

一种新型定向耦合器的耦合性质

文章介绍了一种新型的耦合器—左右手组合介质定向耦合器。该耦合器的主传输线采用传统的微带线结构,而耦合电路则采用近年来引起广泛注意的左右手组合材料。左右手组合材料采用在微带线上加载集总元件变容二极管实现了耦合频率的连续移动。实验发现,当加载变容二极管的电压升高时,耦合强度随之变化且耦合频率向高频方向移动。     

平行耦合线定向耦合器的设计

阐述了平行耦合线定向耦合器的工作原理和设计过程.根据耦合微带线和耦合带状线的主要特征,分别设计了频率为2.5GHz的平行耦合微带线定向耦合器和平行耦合带状线定向耦合器.根据给定耦合器的技术指标,确定耦合器的类型、结构.利用ADS软件环境设计了平行耦合线定向耦合器的电路模型,并对定向耦合器的S参数进行仿真、优化,已达到预期的设计要求.由仿真结果可以看出,在频带范围内,耦合带状线定向耦合器的耦合性能优于耦合微带线定向耦合器.     

LTCC定向耦合器的研制

LTCC（低温共烧陶瓷）技术是无源元件集成的主流技术之一。本文介绍了一种基于LTCC工艺的定向耦合器的设计原理和方法。该定向耦合器是一种采用侧边耦合的传输线型耦合器。在电路结构上,通过把两个弱耦合器进行对称串联的方式满足了5dB紧耦合的要求,并使方向性有了较大改善。在研制过程中,利用ADS软件对电路进行了仿真和优化,采用LTCC过孔互联结构,避免使用键合线,从而提高了可靠性。     

光电耦合高压MOS电路及其应用

一、光电耦合高压MOS电路的结构原理 我们采用混合集成技术研制成功的光电耦合高压MOS电路,不仅可以实现输入输出间在电气上的隔离,还可以实现低压输入转换和控制高压输出,从而大大地扩展了光电耦合器     

小型化高方向性的微带双定向耦合器设计

为解决弱耦合时微带平行耦合线定向耦合器方向性低的问题,提出了适用于大功率场合的小型化高方向性微带双定向耦合器。基于传统四分之一波长平行耦合三线微带双定向耦合器结构,采用扇形微带电容加载可明显减小耦合器尺寸并增大隔离度,通过耦合边缘引入锯齿结构进一步提高了方向性。负载电阻采用扇形微带短截线接地设计,避免电气化过孔,使得加工更加简单。设计了一个中心频率为915 MHz、耦合度为20 dB 的微带双定向耦合器,利用HFSS 仿真软件对耦合器结构进行优化设计,并做了实物加工和测试。实测结果表明,在中心频率处耦合度为20.2 dB,方向性达到32.1 dB;在0.74~1.35 GHz 频带内,输入匹配良好,耦合度波动小于0.5 dB,方向性高于20 dB。     

小孔耦合型双通道太赫兹波导定向耦合器设计

提出了一种小孔耦合型双通道太赫兹波导定向耦合器,采用新颖的阶梯结构,将两个单通道耦合器结合,可在双通道内实现相同的耦合输出。研究结果表明,在180~260 GHz的频率范围内,该耦合器的耦合度为10 dB,输出最大误差小于1.6 dB,回波损耗大于25 dB,隔离度大于35 dB,相对带宽达到36%。与传统的太赫兹波导定向耦合器相比,该耦合器能够实现双通道的耦合输出,在太赫兹系统中可用于双通道的功率检测、功率合成与分配。     

一种基于耦合线和环形微带线的负群时延电路

负群时延电路(NGDC)在微波系统中有着广泛应用,文中提出了一种基于有损耦合线和环形微带线的负群时延电路。该电路由耦合线和微带传输线组成。基于射频领域中偶模-奇模分析方法,分析该电路的偶模和奇模的输入导纳,得到电路的S 参数。利用HFSS 电磁仿真软件对该负群时延电路结构做了优化设计,实物加工并测试。测试结果表明:在中心频率2.36 GHz 时,该电路的负群时延值约为-1.4 ns,插入损耗S21约为-3.9 dB,反射系数S11约为-9.5 dB,实测与仿真结果吻合。这种新颖的负群时延电路结构简单、信号损耗小、易于加工,可用于微波和无线通信等领域。     

一种结构新颖的微波高功率定向耦合器

介绍一种结构新颖的微波高功率定向耦合器.该耦合器主线采用波导结构承受功率大,副线采用同轴结构对外连接方便,耦合机构采用单个圆孔实现,整个耦合器设计巧妙,结构简单,便于加工,易于装配,不用调试,指标好,可靠性高,特别适用于高功率、弱耦合、双向取样的场合.     

什么是光电耦合器？

光电耦合器也称为光电隔离器或光耦合器,有时简称光耦。这是一种以光为耦合媒介,通过光信号的传递来实现输入与输出间电隔离的器件,可在电路或系统之间传输电信号,同时确保这些电路或系统彼此间的电绝缘。     

Group Delay Equalized UWB InGaP/GaAs HBT MMIC Amplifier Using Negative Group Delay Circuits

A negative group delay (NGD) circuit has been employed to equalize a group delay variation in a broadband ultra-wideband (UWB) InGaP/GaAs heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) amplifier. Using the NGD circuit, a part of a salient group delay characteristic in the operation band of broadband amplifiers can be suppressed without an increase of the entire group delay. The MMIC amplifier has a steep group delay increase in the lower frequency region of the full-band UWB band (3.1-10.6 GHz) due to the sum of phase variations near the cutoff frequencies of the HBTs. The NGD circuit has been inserted to reduce this increase of the group delay in the UWB band. By adding a three-cell NGD circuit while considering input and output matching at the input side of the MMIC amplifier, the group delay variation is decreased by 78%. However, gain was also decreased by insertion of the multistage NGD circuit. In an attempt to avoid this decrease in gain, a one-cell NGD circuit was inserted into the feedback loop of the MMIC amplifier, and as a result, we were able to decrease the group delay variation by 79%, with minimal gain deterioration.     

Unity direct chain with feedback series impedance based innovative negative group delay circuit

An innovative negative group delay (NGD) circuit theory on unity direct chain (UDC) topology is developed in this paper. The NGD UDC cells are based on the operational amplifier adder with feedback series impedance. Innovative topologies of high-pass NGD UDC cell composed of RL-series network, all-pass RC-parallel network and low-pass RC-series network are identified. It is a first time that all-pass NGD original topologies are defined. NGD analyses and synthesis methods of each NGD UDC cells are provided. The UDC cell based NGD functions are validated with SPICE simulations. The proofs-of-concept (POC) of UDCs behave as all-pass and low-pass NGD functions with group delay equal to −1 ms at very low frequencies. The low-pass NGD cut-off frequency is 424 Hz. The high pass NGD circuit generates −1 µs at the optimal NGD frequency of about 5.15 kHz. Further analysis of the operational amplifier gain and bandwidth effects is performed. The operational amplifier gain affects significantly the NGD level and bandwidth for the all considered UDC cells. Nevertheless, only the RC-parallel feedback based UDC cell is particularly sensitive to the operational bandwidth.     

负群时延电路研究综述：特征、现状与展望

近年来,负群时延电路由于其异常的电磁波传播特性及广泛的应用前景备受关注.首先,介绍了负群时延与超光速现象的相关概念,阐述了负群时延现象的产生机理及负群时延电路的频域特征;然后,重点讨论了基于左手材料、谐振器与耦合微带线3种主要负群时延电路的组成形式与特点;指出了目前电路的主要问题在于其固有的高损耗、窄带宽特点及负群时延值极限;最后,对负群时延电路未来的研究方向进行了展望,以期为负群时延电路的研究与应用提供一定的参考.     

G<Subscript>m</Subscript>-boosted current-reuse inductive-peaking common source LNA for 3.1–10.6 GHz UWB wireless applications in 32 nm CMOS

This paper presents a simple electronic circuit which provides negative group delay (NGD). The proposed circuit is built around the current-feedback operational-amplifier and uses grounded resistors and capacitors. The proposed circuit has a high input impedance and a low output impedance. Thus, obtaining relatively long NGDs is feasible by cascading several circuits. Experimental and simulation results that confirm the functionality of the proposed circuit are included.     

Active Microwave Circuit With Negative Group Delay

In this letter, we report on the design, simulation and implementation of an active negative group delay circuit that operates at 1 GHz with a group delay and a gain, respectively, around 2 ns and 2 dB. Analytical formulas are proposed to demonstrate that the adopted topology is able to simultaneously achieve negative group delay (NGD) and gain while fulfilling active device constraints. The theoretical and simulated results are both validated by frequency measurements of a two-stage active microwave circuit.     

Distributed NGD active circuit for RF-microwave communication

This paper is aimed to the investigation on innovative distributed negative group delay (DNGD) circuits for RF communication. Thanks to the analogy between the lumped and distributed circuits, NGD circuit topologies were identified. By using the S-parameter theory, analysis and synthesis methods of these topologies are proposed. The DNGD circuits developed are mainly comprised of a transistor combined with a series resistance ended by a stub. Then, synthesis relations enabling to determine the NGD circuit parameters from the desired NGD and gain values are established. As application, an active phase shifter (PS) operating independently with the frequency based on the cascade of PGD and NGD devices was synthesized. First, an NGD PS with transmission phase of (135 ± 5)° around 2.56 GHz over the bandwidth of about 1.02 GHz was obtained. Then, a two-stage DNGD PS exhibiting 90° with ±10° flatness from 4.1 GHz to 6.8 GHz was designed. The DNGD circuit presented can be used in various telecommunication areas notably for correcting RF/numerical signal delays in the RF-microwave analogue-digital devices.     

Simple method for mitigation of polarization crosstalk in silica planar lightwave circuit directional couplers

Polarization crosstalk in planar lightwave circuit directional couplers can cause significant polarization-dependence in interferometers that use them. We show a simple way to mitigate the polarization crosstalk without incurring a performance penalty or requiring extra fabrication steps. We demonstrate it on a 23-ps Mach-Zehnder delay interferometer.     

Planar lightwave circuit polarization-mode dispersion compensator

In this letter, we fabricated an integrated polarization-mode dispersion compensator on a silica-based planar lightwave circuit that incorporated an endless polarization controller and a fixed polarization dependent delay line. The compensator consisted of polarization beam splitters, thermooptic phase shifters, tunable couplers, and polarization converters. We experimentally confirmed its operation at a data rate of 43 Gb/s     

Miniaturized Dual-Band Hybrid Couplers With Arbitrary Power Division Ratios

Branch-line and rat-race couplers are designed to have dual-band operation with arbitrary power division ratios. An elementary two-port is proposed to imitate the 90^deg section at the two designated frequencies with different characteristic impedances. The two-port consists of a stepped-impedance section with open stubs attached to its two ends, and its circuit parameters are determined by the transmission line theory. The use of the stepped-impedance sections also leads to circuit miniaturization. By the standard microstrip technology, investigated also includes the realizable power division ratios and circuit bandwidths in the two bands, the upper limit of the ratio of the two designated frequencies and the miniaturization factor of the proposed circuit. Hybrid couplers operating at 2.45/5.2 GHz with various power division ratios are designed, fabricated and tested. Experiment results are compared with the theory and simulation.     

Synthesis of coherent two-port lattice-form optical delay-linecircuit

A method is presented for synthesizing a coherent two-port lattice-form optical delay-line circuit that is composed of optical delay lines, directional couplers, and phase shifters. The two bases of the method are the use of a unimodulus para-unitary matrix as a transfer matrix and the division of the transfer matrix into basic component transfer matrices. We succeeded in obtaining a set of recurrent equations with which to calculate circuit parameters to use for designing an optical delay-line circuit with a desired cross-port (through-port) transfer function. In the developed method, it is shown that two-port optical delay-line circuits can have the same transmission characteristics as finite impulse response digital filters with complex expansion coefficients. Three synthesis examples for optical frequency filters are described: a linear-phase Chebyshev filter, a multi-channel selector, and a group-delay dispersion equalizer. It is confirmed that transmission characteristics with a maximum transmittance of 100% can be always synthesized. The allowable parameter error for the synthesized linear-phase Chebyshev filter is also discussed