Heterodyne Digital Control of a High-Frequency Micromechanical Oscillator

2005 ◽  
Vol 128 (3) ◽  
pp. 577-583 ◽  
Author(s):  
Thomas E. Kriewall ◽  
Joseph L. Garbini ◽  
John A. Sidles ◽  
Jonathan P. Jacky
Keyword(s):  
High Frequency ◽  
Digital Control ◽  
Narrow Band ◽  
Band System ◽  
Digital Signal ◽  
Computational Effort ◽  
Pass Band ◽  
Magnetic Resonance Force Microscopy ◽  
Force Microscopy ◽  
Lock In

In this paper we present heterodyne control as a technique for digital feedback control of a high-frequency, narrowband micromechanical oscillator. In this technique, isolated and synchronized hardware downconversion and upconversion components are used in conjunction with digital signal processing (DSP) to control the oscillator. Heterodyne control offers reduced computational effort for the digital control of high-frequency, narrow band system, the reduction of noise outside the pass-band, and the generation of lock-in amplifier signals. We present heterodyne control with design criteria in the context of magnetic resonance force microscopy (MRFM) cantilever control. Finally, we present experimental results of heterodyne control applied to an emulated radio-frequency microcantilever system.

Enhanced Detection Sensitivity with Pulsed Laser Digital Signal Integration Algorithm

2006 ◽  
Author(s):  
A.C.T. Quah ◽  
J.C.H. Phang ◽  
L.S. Koh ◽  
S.H. Tan ◽  
C.M. Chua
Keyword(s):  
Fault Localization ◽  
Pulsed Laser ◽  
Digital Signal ◽  
Detection Sensitivity ◽  
Signal Integration ◽  
Laser Operation ◽  
Frequency Range ◽  
Integration Algorithm ◽  
Detection Systems ◽  
Lock In

Abstract This paper describes a pulsed laser induced digital signal integration algorithm for pulsed laser operation that is compatible with existing ac-coupled and dc-coupled detection systems for fault localization. This algorithm enhances laser induced detection sensitivity without a lock-in amplifier. The best detection sensitivity is achieved at a pulsing frequency range between 500 Hz to 1.5 kHz. Within this frequency range, the algorithm is capable of achieving more than 9 times enhancement in detection sensitivity.

Nanoscale Capacitance and Capacitance-Voltage Curves for Advanced Characterization of Electrical Properties of Si and GaN Structures Using Scanning Microwave Impedance Microscopy

2016 ◽  
Author(s):  
Stuart Friedman ◽  
Oskar Amster ◽  
Yongliang Yang ◽  
Fred Stanke
Keyword(s):  
Process Development ◽  
Advanced Characterization ◽  
Electrical Measurement ◽  
Depletion Layer ◽  
Doped Semiconductors ◽  
Force Microscopy ◽  
Nano Scale ◽  
Capacitance Voltage ◽  
Systematic Response ◽  
Lock In

Abstract The use of Atomic Force Microscopy (AFM) electrical measurement modes is a critical tool for the study of semiconductor devices and process development. A relatively new electrical mode, scanning microwave impedance microscopy (sMIM), measures a material’s change in permittivity and conductivity at the scale of an AFM probe tip [1]. sMIM provides the real and imaginary impedance (Re(Z) and Im(Z)) of the probe-sample interface. By measuring the reflected microwave signal as a sample of interest is imaged with an AFM, we can in parallel capture the variations in permittivity and conductivity and, for doped semiconductors, variations in the depletion-layer geometry. An existing technique for characterizing doped semiconductors, scanning capacitance microscopy, modulates the tip-sample bias and detects the tip-sample capacitance with a lock-in amplifier. A previous study compares sMIM to SCM and highlights the additional capabilities of sMIM [2], including examples of nano-scale capacitance-voltage curves. In this paper we focus on the detailed mechanisms and capabilities of the nano-scale C-V curves and the ability to extract semiconductor properties from them. This study includes analytical and finite element modeling of tip bias dependent depletion-layer geometry and impedance. These are compared to experimental results on reference samples for both doped Si and GaN doped staircases to validate the systematic response of the sMIM-C (capacitive) channel to the doping concentration.

Detection of liquids by magnetic resonance force microscopy in the gradient-on-cantilever geometry

2019 ◽  
Vol 298 ◽  
pp. 85-90
Author(s):  
Sebastian Schnoz ◽  
Alexander Däpp ◽  
Andreas Hunkeler ◽  
Beat H. Meier
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Force Microscopy ◽  
Force Microscopy

Rapid Recovery of Wide-Bandwidth Photothermal Signals via Homodyne Photothermal Spectrometry: Theory and Methodology

1993 ◽  
Vol 47 (4) ◽  
pp. 489-500 ◽  
Author(s):  
J. F. Power ◽  
M. C. Prystay
Keyword(s):  
High Frequency ◽  
Low Cost ◽  
Signal Recovery ◽  
Wide Bandwidth ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Filter Output ◽  
Low Pass ◽  
Four Quadrant ◽  
Lock In

Homodyne photothermal spectrometry (HPS) is a very wide bandwidth signal recovery technique which uses many of the elements of lock-in detection at very low cost. The method uses a frequency sweep, with a high-frequency bandwidth of up to 10 MHz, to excite a linear photothermal system. The response sweep of the photothermal system is downshifted into a bandwidth of a few kilohertz by means of in-phase mixing with the excitation sweep with the use of a four-quadrant double-balanced mixer and a low-pass filter. Under conditions derived from theory, the filter output gives a good approximation to the real part of the photothermal system's frequency response, dispersed as a function of time. From a recording of this signal, the frequency and impulse response of the photothermal system are rapidly recovered at very high resolution. The method has been tested with the use of laser photopyroelectric effect spectrometry and provides an inexpensive, convenient method for the recovery of high-frequency photothermal signals.

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