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An improved Nauta transconductor, with output resistance for differential-mode output signals insensitive to process and tuning voltage variations, is presented in this paper. Comparing with the classical Nauta transconductor, the proposed transconductor introduces 4 auxiliary inverters only. It can increase the differential-mode output resistance, and keep the common-mode output resistance nearly...
This paper proposes the design, simulation and analysis of RF MEMS varactor for VCO applications for microwave frequencies. The varactors are parallel plate capacitors using electrostatic actuation for tuning. The designed varactors have been simulated using Coventorware and optimized in terms of dimensions to suit CMOS voltages. The varactors have been analyzed for the influence of plate thickness,...
We analyze a Π-network for tunable antenna impedance matching in 4G mobile communications. Fundamental limits on designability and practical limits on implementation of the network are presented. The performance of the network is evaluated in terms of coverage (the area on Smith chart that can be matched) and the maximum achievable tuning bandwidth. We also derive the required component values and...
A transformer based multiple coupled LC tanks model for on-chip VCO design is introduced. The merits of adoption multiple coupled LC tanks can be Q factor enhancement for the equivalent LC tank of VCO, low power consumption, better amplitude swing and broad tuning range can be obtained. As an illustration case two low power Ku band VCOs using dual LC-tanks with/without feedback designed using a 0...
The paper presents a method for design of LC cross-coupled oscillators based on an open loop technique and its practical application leading to a high frequency CMOS oscillator prototype. Thanks to the proposed approach, the main circuit parameters such as loaded quality factor (responsible for phase noise performance of LC oscillator) and steady-state oscillation amplitude, can be extracted without...
A 4th order RF bandpass sigma delta modulator (BPSDM) centered at 2.4GHz ISM band based on integrated transmission lines (ITLs) is presented for the first time. The modulator consists of two tunable capacitively-loaded transmission line resonators with active Q-enhancement. As a result, the design of noise transfer function (NTF) is simplified and the degradation in performance due to the jitter noise...
This paper presents a 61 GHz push-push VCO with an integrated divide-by-eight divider and an output buffer in a 130 nm SiGe BiCMOS process. The VCO core features a differential Colpitts topology with coupled inductors to improve phase noise performance. Eight sub-bands are realized by three digital tuned varicaps, which are placed in parallel with the analog tuned varicap. Its tuning range is 60.85–63...
This paper presents a wide tuning range sub THz oscillator based on triple push operation. The triple push action combined with the use of slow coplanar waveguide structures and artificial dielectric transmission lines in the passive network results in a 15 GHz tuning range with an f0 of 220GHz using 65nm CMOS technology. The optimization procedure for the oscillator and passives modeling is outlined...
A tunable Q-enhanced bandpass filter is presented. The Q of the passive inductors that form the filter resonators is enhanced using a cross-coupled differential pair of transistors which is degenerated by a negative resistance. This technique allows compensation of frequency dependent inductor losses and ensures the Q-enhanced LC resonators to have frequency behaviour close perfectly ideal in the...
This paper presents a programmable low-pass filter implemented with log-domain building blocks; the blocks have Externally Linear Internally Nonlinear (ELIN) structures derived using LIN-ELIN transformations. The order of the proposed filter transfer function can be set to 3rd, 4th or 5th by a digital control word; the main filter parameters can be tuned/adjusted by using the bias currents of the...
A high-Q radiation-sensitive varactor design based on fully-depeleted silicon-on-insulator (FDSOI) for telemetric readout systems is described. A multi-finger device design is evaluated, and the design parameters for maximizing tuning range and quality factor are simulated. Varactors with Lg = 300 nm and tSOI = 20 nm are found to provide 2.5∶1 capacitance tuning range and Q > 100 at ƒ = 1 GHz.
This paper describes the design of a 5 GHz cross-coupled LC VCO implemented in the single-supply S35D4M5 0.35 μm BiCMOS process by Austriamicrosystems. The paper further discusses the phase noise performance of various MOSFET-based current source topologies when implemented within the VCO. MOSFET current source characteristics such as flicker noise, device numbers, feedback, and the output resistance...
This paper presents a method of regulation and maximization of Q-factor in anti-phase driven tuning fork MEMS. Non-symmetric regulation of stiffness in coupled 2-DOF resonators using the negative electrostatic spring effect is shown to adjust the momentum misbalance caused by fabrication imperfections in nominally symmetric structures. Balancing the structure through stiffness matching minimizes the...
The low density of states in graphene makes it possible for the quantum capacitance to be of the same order of magnitude as the oxide capacitance for experimentally achievable gate dielectric thicknesses [1]. This property, combined with the fact that the density of states varies as a function of energy, means that the capacitance in a metal-oxide-graphene capacitor can be tuned by varying the carrier...
We present a 5.9-to-7.8 GHz voltage-controlled oscillator (VCO) fabricated in a 65 nm CMOS technology and assembled in a chip-scale embedded Wafer Level Ball-Grid-Array (eWLB) package. The VCO uses a high-quality LC-tank inductor, realized in the fan-out area of the package. This inductor achieves a quality factor of 28 at a frequency of 6.5 GHz. Using this high-Q inductor it was possible to reduce...
This paper reports on the design, fabrication, and characterization of a high-frequency single proof-mass dual-axis gyroscope. The hollow-disk pitch-and-roll resonant gyroscope has electrostatically tunable in-plane and out-of-plane resonance modes to enable mode-matched operation at ∼ 0.9MHz in the presence of process non-idealities such as thickness variations of the SOI wafer. A prototype device...
This paper reports on a novel approach to control losses in torsional microresonators for applications that require high precision. This methodology is demonstrated through realizing an array of electrostatically coupled microresonators with independent tuning of both quality factor and resonant frequency. Different anchor designs were used to evaluate their roles on effectiveness of the technique...
The helical inductor is a three-dimensional multi-layer inductor with relatively higher quality factor and self-resonance frequency compare with other multi-layer inductors. A new dual-mode coupled-inductor VCO based on helical inductors is proposed, which is able to work on 5GHz and 10GHz band. Because of the helical inductors used, the proposed VCO is much more area-efficient than previous coupled-inductor...
Interrelation of the quality factor, the lower bound on the quality factor (Qlb(ω)), and bandwidth was examined for an electrically small antenna with coupled impedance resonances around its antiresonance. Bands corresponding to the resonances and the total bandwidth of the antenna are limited by values of Qlb−1(ω) calculated at frequencies of their centers. The approximate quality factor determined...
Orthogonalization consumes much of the run time of many iterative methods for solving sparse linear systems and eigenvalue problems. Commonly used algorithms, such as variants of Gram-Schmidt or Householder QR, have performance dominated by communication. Here, "communication" includes both data movement between the CPU and memory, and messages between processors in parallel. Our Tall Skinny...
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