Active damping in precision equipment using piezo

In this paper, the rotational vibration in the linearly actuated precision machines with low damping is discussed. This so called Rocking mode is e.g. caused by the compliance in the guiding system of a linear actuator and leads to a long settling time of the end-effector. Another problem occurs when a feedback motion controller is applied to the plant. Complex poles present in the loop transfer that are close to the imaginary axis due to low damping, are destabilized by a relatively small gain. A possible solution is actively damping the resonance frequencies. By flattening the resonance peaks, the bandwidth of the system can increase without the danger of instability. In turn, this allows for higher integral gain in the motion control algorithm

A Spectral-Scanning Magnetic Resonance Imaging (MRI) Integrated System

An integrated spectral-scanning magnetic resonance imaging (MRI) technique is implemented in a 0.12μm SiGe BiCMOS process. This system is designed for small-scale MRI applications with non-uniform and low magnetic fields. The system is capable of generating customized magnetic resonance (MR) excitation signals, and also recovering the MR response using a coherent direct conversion receiver. The operation frequency is tunable from DC to 37MHz for wide-band MRI and up to 250MHz for narrow-band MR spectroscopy

A Spectral-Scanning Nuclear Magnetic Resonance Imaging (MRI) Transceiver

An integrated spectral-scanning nuclear magnetic resonance imaging (MRI) transceiver is implemented in a 0.12 mum SiGe BiCMOS process. The MRI transmitter and receiver circuitry is designed specifically for small-scale surface MRI diagnostics applications where creating low (below 1 T) and inhomogeneous magnetic field is more practical. The operation frequency for magnetic resonance detection and analysis is tunable from 1 kHz to 37 MHz, corresponding to 0-0.9 T magnetization for ^1H (hydrogen). The concurrent measurement bandwidth is approximately one frequency octave. The chip can also be used for conventional narrowband nuclear magnetic resonance (NMR) spectroscopy from 1 kHz up to 250 MHz. This integrated transceiver consists of both the magnetic resonance transmitter which generates the required excitation pulses for the magnetic dipole excitation, and the receiver which recovers the responses of the dipoles

Near-Field Direct Antenna Modulation (NFDAM) transmitter at 2.4GHz

A near-field direct antenna modulation (NFDAM) transmitter at 2.4GHz is demonstrated on a microstrip setting. The transmitter is capable of transmitting information in a direction-dependent fashion by sending the correct signal constellation only in the desired direction while leaving the signal constellation points scrambled in undesired directions. This direction-dependent constellation scrambling nature of the NFDAM systems prevents undesired receivers to correctly demodulate the signal transmitted to a desired receiver at a specific direction

Near-field direct antenna modulation

NFDAM systems provide a unique solution for transmitting highly secured direction-dependent data and hence preventing eavesdroppers from properly demodulating the signal. A 60-GHz proof-of-concept chip was designed and measured

Transmitter Architectures Based on Near-Field Direct Antenna Modulation

A near-field direct antenna modulation (NFDAM) technique is introduced, where the radiated far-field signal is modulated by time-varying changes in the antenna near-field electromagnetic (EM) boundary conditions. This enables the transmitter to send data in a direction-dependent fashion producing a secure communication link. Near-field direct antenna modulation (NFDAM) can be performed by using either switches or varactors. Two fully-integrated proof-of-concept NFDAM transmitters operating at 60 GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach

Active damping of vibrations in high-precision motion systems

Technology advancements feed the need for ever faster and more accurate industrial machines. Vibration is a significant source of inaccuracy of such machines. A light-weight design in favor of the speed, and avoiding the use of energy-dissipating materials from the structure to omit any source of inaccuracy, contribute to a low structural damping.\ud The goal of this research is to investigate the addition of damping to the rotational vibration mode of a linearly actuated motion system to\ud • achieve a shorter settling time in the transient response of the plant to a commanded motion\ud • increase the achievable closed-loop motion-control bandwidth\ud This thesis starts by showing the influence of damping on the stability of motion systems, for P(I)D-type motion controllers. Furthermore, a set of guidelines is presented that can be used for a mechatronic design of an active-damping loop. It is shown that collocated active damping increases the damping of both the poles and the zeros of the motion-control loop. This allows for a higher increase of motion-control bandwidth than when the same actuator is used in both the motion-control loop and the active-damping loop. The chosen control algorithm for collocated active damping is integral force feedback. This combination results in a robustly stable closed-loop system. The effect of active damping on the end-effector dynamics of a motion system is analyzed extensively in simulation. The performance improvement by damping in the transient behavior of the plant is shown using a test setup that suffers from a rotational vibration mode

An Integrated Subharmonic Coupled-Oscillator Scheme for a 60-GHz Phased-Array Transmitter

This paper describes the design of an integrated coupled-oscillator array in SiGe for millimeter-wave applications. The design focuses on a scalable radio architecture where multiple dies are tiled to form larger arrays. A 2 × 2 oscillator array for a 60-GHz transmitter is fabricated with integrated power amplifiers and on-chip antennas. To lock between multiple dies, an injection-locking scheme appropriate for wire-bond interconnects is described. The 2 × 2 array demonstrates a 200–MHz locking range and 1 × 4 array formed by two adjacent chips has a 60-MHz locking range. The phase noise of the coupled oscillators is below 100 dBc/Hz at a 1-MHz offset when locked to an external reference. To the best of the authors’ knowledge, this is the highest frequency demonstration of coupled oscillators fabricated in a conventional silicon integrated-circuit process

Theory of multidimensional Laplace transforms and boundary value problems

In this dissertation, several theorems on multidimensional Laplace transforms are developed. These theorems are applied to most commonly used special functions to obtain many new two and three dimensional Laplace transform pairs from known one and two dimensional Laplace transforms. Last, some boundary value problems characterized by linear partial differential equations involving heat and wave equations are explicitly solved by using the obtained results to illustrate the applications

A 6-to-18 GHz tunable concurrent dual-band receiver front end for scalable phased arrays in 130nm CMOS

This paper presents a study and design of tunable concurrent dual-band receiver. Different system architectures and building blocks have been compared and analyzed. A tunable concurrent dual-band receiver front end has then been fabricated and characterized. It operates across a tri-tave 6-18 GHz bandwidth with a nominal 17-25 dB conversion gain, worst-case -15 dBm IIP3, and worst-case -24.5 dBm ICP 1 dB