A Si MMIC compatible ferroelectric varactor shunt switch for microwave applications

This letter describes a ferroelectric thin-film based varactor shunt switch, for microwave and millimeterwave switching applications. Our implementation is based on a coplanar waveguide transmission line shunted by a ferroelectric varactor. The concept of switching ON and OFF is based on the dielectric tunability of the ferroelectric barium strontium titanium oxide (BST) thin-films. From experimental verification, the isolation of a switch with a varactor area of 75/spl mu/m/sup 2/ was approximately 20dB at 35GHz and the insertion loss was below 4.5dB up to 35GHz. This letter addresses the design and experimental verification of the first ferroelectric varactor shunt switch with an Si monolithic microwave integrated circuit compatible process.     

2.4 GHz continuously variable ferroelectric phase shifters using all-pass networks

Continuously variable ferroelectric (BST on sapphire) phase shifters based on all-pass networks are presented. An all-pass network phase shifter consists of only lumped LC elements, and thus the total size of the phase shifter is kept to less than 2.2 mm /spl times/ 2.6 mm at 2.4 GHz. The tunability (C/sub max//C/sub min/) of a BST interdigital capacitor is over 2.9 with a bias voltage of 140 V. The phase shifter provides more than 121/spl deg/ phase shift with the maximum insertion loss of 1.8 dB and the worst case return loss of 12.5 dB from 2.4 GHz to 2.5 GHz. By cascading two identical phase shifters, more than 255/spl deg/ phase shift is obtained with the maximum insertion loss of 3.75 dB. The loss figure-of-merit of both the single- and double-section phase shifters is over 65/spl deg//dB from 2.4 GHz to 2.5 GHz.     

Microwave Varactor Tuned Transistor Oscillator Design

An analysis is made of the common base microwave transistor oscillator circuit which uses a varactor in series with the colIector to tune over octave bandwidths. Equations are derived giving the required feedback capacitances and resonating elements required for octave tuning. Normally, the collector-emitter capacitance C/sub ce/ is made approximately equal to the transistor collector capacitance C/sub c/. The emitter-base capacitance C/sub eb/ is important only at very high frequencies. It is shown that a high-Q varactor must be used and that only a limited amount of collector-base capacitance C/sub cb/ may be added if the circuit is to be resonated over an octave. The output power for such a circuit is normally about 1/5 the maximum power available from the transistor. Experimental oscillators were made from 0.5 to 1 GHz and 1 to 2 GHz which substantially verified the analysis. Using the TIXS13 transistor, an output power of 200 mW was obtained from 430 to 860 MHz tuning from -2 to -115 volts. In the 1 to 2 GHz range a TIXS13 transistor oscillator was tuned from 1.09-1.96 GHz with about 40 mW power tuning from -2 to -115 volts. By use of a lower case capacitance varactor, the 1 to 2 GHz oscillator could be made to tune over the full octave.     

BST薄膜铁电移相器研究进展

钛酸锶钡(BST)薄膜因其具有高的介电调谐量,相对低的损耗tgδ和快的开关速度,在微波移相器的应用中显示出巨大优势。介绍了改善BST薄膜的介电性能的有效方法,衬底材料的选择,以及BST薄膜铁电移相器的结构类型和研究进展。     

Wideband VCO With Simultaneous Switching of Frequency Band, Active Core, and Varactor Size

As the tuning range of integrated LC-VCOs increases, it becomes difficult to co-design the active negative resistance core and the varactor size optimally for the complete frequency range. The presented VCO design solves this by adjusting the size of the negative resistance transistors with a switched active core, with the additional benefit that this reduces parasitics and hence allows to achieve better phase noise and an even higher tuning range. Also the VCO gain variations are counteracted by employing an analog varactor that can change in size. The implementation in 0.13-mum CMOS shows a tuning range from 3.1 to 5.2 GHz, with a power consumption varying accordingly from 7.7 to 2.1 mA from a 1.2 V supply. The measured phase noise is -118 dBc/Hz at 1 MHz from a 4-GHz carrier.     

Electrically tunable split-ring resonators at microwave frequencies based on barium-strontium-titanate thick films

Split-ring resonators (SRRs) implemented using ferroelectric materials to modify their resonance frequency by means of a tuning voltage are presented for the first time. SRRs have been used to load a microstrip transmission line on a multilayered substrate including a thick film of barium-strontium-titanate (BST) to obtain a tunable stopband response. The characteristics of the BST layer allow the application of 140 V as tuning voltage to obtain frequency tunability values of around 12.5 . The applied technology is suitable for the fabrication of cost-effective and reliable planar microwave devices.     

A 5-6-GHz bipolar quadrature-phase Generator

A wide-band fully monolithic quadrature-phase generator is implemented. It consists of a bipolar frequency doubler with differential outputs and a regenerative divider with 5 mV/sub rms/ maximum sensitivity. Measured residual phase noise is 相似文献   

Composite right/left handed transmission line phase shifter using ferroelectric varactors

A composite right/left handed (CRLH) transmission line (TL) phase shifter, using ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors as tunable element, is presented for the first time. It is theoretically and experimentally demonstrated how the unique features of CRLH TLs, enables a differential phase shift with flat frequency dependence around the center frequency. The experimental prototype is a coplanar design integrated on a high resistive Si substrate. It includes four CRLH T-unit cells and has a physical length of 3850/spl mu/m. The ferroelectric varactors are realized in parallel plate version. Under 15-V dc bias applied over each varactor, the differential phase shift is flat around 17GHz and has an absolute value of 50/spl deg/.     

Fixed-Beam Frequency-Tunable Phase-Reversal Coplanar Stripline Antenna Array

A fixed-beam frequency-tunable coplanar stripline (CPS) antenna array using the phase reversal technique and varactor diodes tuning is presented. The antenna array is composed of plurality of half-wavelength CPS sections interconnected by phase reversing crossovers. These crossovers have two functions: they serve as the radiators (small dipoles) of the array and also provide their own required in-phase excitations for broadside radiation. Two microstrip-to-CPS transitions for excitation of the balanced input/output antenna array are implemented and compared. A six-element array is demonstrated theoretically and experimentally, with 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation using a back reflector. Moreover, shunt varactor diodes are incorporated along the CPS structure to achieve frequency tuning through a bias voltage control while broadside radiation patterns remain fixed. The return loss and the radiation patterns at several frequencies are presented, and up to 50% tuning range is obtained. The proposed antenna array is simple and uniplanar with small lateral size, high radiation efficiency and high directivity. In addition, it uses a very simple biasing circuit with high DC-RF isolation. Its balanced input/output makes it suitable for RF system integration and active integrated antenna design.     

A 0.5 V LC-VCO with improved varactor tuning technique for WSN

A 0.5 V LC-VCO implemented in 0.18 μm CMOS technology for wireless sensor network is described in this paper. An improved varactor tuning technique is proposed to decrease low frequency noise up-conversion and AM–FM phase noise of VCO, also it can increase Q of LC tank and reduce power consumption of VCO. For coarse tuning of VCO, it can increase the varactor control voltage variation range. For fine tuning of VCO, it can reduce the varactor nonlinearity. The measured tuning range is 4.58–5.26 GHz and power consumption is 2.2 mW. The measured phase noise is ?114 dBc/Hz at 1 MHz frequency offset from a 4.8 GHz carrier.     

A 38% Tuning Bandwidth Low Phase Noise Differential Voltage Controlled Oscillator Using a 0.5 $mu$m E/D-PHEMT Process

This paper presents a 38% tuning bandwidth low phase noise differential voltage controlled oscillator (VCO) using a 0.5 $mu$m enhancement/depletion-pseudomorphic high-electron mobility transistor (E/D-PHEMT) process. The proposed VCO is based on a differential topology with two common-gate transistors. To achieve a wide tuning range with low phase noise, varactor in the VCO core employs the E-mode PHEMT device. The frequency of the VCO is from 18.8 to 27.5 GHz with a tuning bandwidth of 38% and an output power of higher than 5 dBm. The VCO demonstrates a phase noise of ${-}109$ dBc/Hz at 1 MHz offset frequency. This circuit can be compared with the VCOs fabricated using the advanced InP HBT technologies.      

A low-phase-noise reference oscillator with integrated pMOSvaractors for digital satellite receivers

A low-phase-noise LC reference oscillator (RO) for use in digital satellite receivers is described. This RO is an essential building block of a double-loop wide-band tuning system that reduces the phase noise of integrated quadrature voltage-controlled oscillators (VCOs) required for zero-IF receivers. In order to achieve a high degree of integration the RO is implemented using integrated varactors. Three varactor options which are available in a standard 11-GHz f_t bipolar technology are investigated: the p-n junction of an NPN, an active varactor circuit, and a pMOS varactor. Experimental results show that the integrated pMOS varactor combined with external inductors is the preferred choice to implement the resonator of the low-phase-noise RO. The achieved tuning range is 225-310 MHz. Carrier-to-noise levels of more than 87 dBc/Hz at 10-kHz offset are measured. The performance is realized with a RO dissipation of 14 mW at a supply voltage of 3.5 V     

Large-signal analysis of MOS varactors in CMOS -G/sub m/ LC VCOs

MOS varactors are used extensively as tunable elements in the tank circuits of RF voltage-controlled oscillators (VCOs) based on submicrometer CMOS technologies. MOS varactor topologies include conventional D = S = B connected, inversion-mode (I-MOS), and accumulation-mode (A-MOS) structures. When incorporated into the VCO tank circuit, the large-signal swing of the VCO output oscillation modulates the varactor capacitance in time, resulting in a VCO tuning curve that deviates from the dc tuning curve of the particular varactor structure. This paper presents a detailed analysis of this large-signal effect. Simulated results are compared to measurements for an example 2.5-GHz complementary -G/sub m/ LC VCO using I-MOS varactors implemented in 0.35-/spl mu/m CMOS technology.     

A Wide Tuning-Range CMOS VCO With a Differential Tunable Active Inductor

By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-$muhbox m$CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from$-$101 to$-$118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of$hbox 150times hbox 300 muhbox m^2$.     

VCO电路测试新型BST电容器的可变电容特性

基于新型BST电容器的变容机理,采用集成芯片MC12148设计VCO(压控震荡器)测试电路,通过测量不同控制电压对应的频率,计算出材料的电容与介电常数,研究了新型BST的压控特性,推导出该BST材料的电压与电容关系式。结果显示:新型BST材料加正反偏压电容都发生变化;最大耐压值为40 V;其电容调谐率与压控灵敏度都很小,分别为10.691%和5.717 kHz/V;材料应用在频率合成器的微调上,可提高合成频率的灵敏度与精度。     

A 50 dB variable gain amplifier using parasitic bipolar transistorsin CMOS

A variable-gain amplifier (VGA) with a gain range of 50 dB has been implemented in a standard 3 μm CMOS process using parasitic lateral and vertical bipolar transistors to form the core of the circuit. The bipolar transistors had been characterized extensively. The VGA has a bandwidth larger than 3 MHz over the whole gain range and operates on a single 5 V power supply. The active area is about 0.8×0.9 mm²     

A low-phase-noise LC-VCO with an enhanced-Q varactor for use in a high-sensitivity GNSS receiver

An LC-VCO with an enhanced quality factor(Q) varactor for use in a high-sensitivity GNSS receiver is presented.An enhanced A-MOS varactor is composed of two accumulation-mode MOS(A-MOS) varactors and two bias voltages,which show the improved Q and linearization capacitance-voltage(C-V) curve.The VCO gain(K_(vco)) is compensated by a digital switched varactors array(DSVA) over entire sub-bands.Based on the characteristics of an A-MOS,the varactor in a DSVA is a high Q fixed capacitor as it is switched off,and a moderate Q tuning varactor when it is switched on,which keeps the maximal Q for the LC-tank.The proposed circuit is fabricated in a 0.18μm 1P6M CMOS process.The measured phase noise is better than -122 dBc/Hz at a 1 MHz offset while the measured tuning range is 58.2%and the variation of K_(VCO) is close to±21%over the whole of the sub-bands and the effective range of the control voltage.The proposed VCO dissipates less than 5.4 mW over the whole operating range from a 1.8 V supply.     

A low phase noise silicon 18-GHz push-push VCO

The design and measurement of a push-push voltage controlled oscillator (VCO) at 18.66-18.3 GHz are presented in this paper. The circuit includes two packaged silicon transistors (Siemens BFP 540F) and a microstrip resonator tuned by two GaAs varactor diodes (M/A-COM ML46580). A 360-MHz tuning range is obtained with an output power of 0-3.1 dBm. The fundamental rejection is around 17 dB for a wide range of collector bias current. The phase noise is below -103 dBc/Hz at 100-kHz offset and below -122 dBc/Hz at 1 MHz for the entire tuning bandwidth.     

A fully differential LC-VCO using a new varactor control structure

This paper presents a fully differential inductor-capacitor voltage-controlled oscillator (LC-VCO) with a new differentially-tuned varactor structure. The proposed LC-VCO has lower phase noise and better robustness to the injected common-mode noise than the differentially-tuned LC-VCO using the previous antiparallel structure. The LC-VCO implemented using 0.5-/spl mu/m SiGe BiCMOS technology is tunable from 4.251 to 4.428 GHz and the measured phase noise is -119 dBc/Hz at 1-MHz offset over the entire tuning range. Its core current is only 1.7 mA at 2.5-V supply voltage.     

有源电阻RTIA红外焦平面读出电路

提出了一种基于有源电阻的电阻反馈跨导放大器(RTIA)红外焦平面读出电路,该电路采用工作在亚阈区的MOS管实现1011 以上的有源大电阻,不仅能与热释电红外探测器的高阻抗良好匹配,而且配合两管共源放大器可针对热释电微弱信号进行高增益电流放大。同时,简单的三管单元结构能够方便地置于像元之下,相比于采用特殊高阻材料实现的RTIA,不附加材料和工艺。经上华0.5 ?滋m CMOS工艺流片验证,在5 V电源电压下,该电路增益40 dB,输出摆幅3 V,在高低温测试下表现出了良好的增益带宽稳定性,适用于PZT和BST等热释电大阵列探测器。