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时间：10-02
整理：3721RD
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In an Atomic Force Microscope (AFM), one of the measuring techniques is non-contact mode. In this mode a sharp tip is brought into close proximity to the surface that is to be imaged. As the tip is brought into resonance, the interaction between the tip and the substrate will alter the resonant frequency. By monitoring this change in frequency we can image the height of the surface with sub nanometre precision.
It is your task to design a Phase Lock Loop (PLL) system that can track the resonance
frequency of the AFM tip and cantilever ensemble. You have available the filter as given in Figure 4.1. The other specifications of the PLL system are:
The natural frequency: 320 kHz
VCO gain: Ko = 1.25 MHz/V = 7.854 Mrad/sec/V
Phase detector gain: Kd = 0.857 V/rad
Amplifier gain: 12
Damping factor: 30.2
Your answer should include:
a) The transfer function of the filter. 4
b) The block diagram of the PLL. 4
c) The transfer function of the PLL. 5
d) The design parameters of the filter.
It is your task to design a Phase Lock Loop (PLL) system that can track the resonance
frequency of the AFM tip and cantilever ensemble. You have available the filter as given in Figure 4.1. The other specifications of the PLL system are:
The natural frequency: 320 kHz
VCO gain: Ko = 1.25 MHz/V = 7.854 Mrad/sec/V
Phase detector gain: Kd = 0.857 V/rad
Amplifier gain: 12
Damping factor: 30.2
Your answer should include:
a) The transfer function of the filter. 4
b) The block diagram of the PLL. 4
c) The transfer function of the PLL. 5
d) The design parameters of the filter.
