Greatly Improved Small Inductance Measurement Using Quartz Crystal Parasitic Capacitance Compensation

Abstract

Generally, quartz crystal inductance frequency pulling in oscillators is very low and therefore is not often used in practice. The new method of improving frequency pullability uses inductance to compensate for quartz stray capacitances. To this end, a special AT fundamental quartz crystal working near the antiresonance frequency is selected. By modifying its equivalent circuit with load inductance and series tuning capacitance, the magnetic sensing of the circuit can be highly improved. The experimental results show that the new approach using the quartz crystal stray capacitance compensation method increases the frequency pulling range (from ≅ 2 kHz/μH to ≅ 600 kHz/μH) by × 300 depending on the type of oscillator, making possible the measurement of nano-magnetic changes.

From Telerobotic towards Nanorobotic Applications

“…The use of a haptic device remarkably improved the communication link between the user and the micro/nano-robot. The main drawback of the presented methods is that they can prevent collision, or provides feeling of touch, only within predefined robotic cell and its environment, while it is very difficult or even impossible to sense or visualise so-called unknown dynamic objects (Matko & Šafarič, 2009), (Matko & Jezernik 2010).…”

Highly Sensitive Dual Quartz Reactance-to-Frequency Transducer

“…At frequencies of 10 and 19 MHz, the resonance frequency in relation to change Ω is higher (at Ω ≅ 1.0022) due to additional parasitic capacitance and inductance influences, however, compared to one single crystal it remains more or less the same. Reduced total reactance (due to connection in parallel) results in an easier crystal oscillation and pulling range increase by approximately 200% [6].…”

“…The joining of f 0 and ∆f 0 (C x ) gives (12) which represents f o1 . The particularity of this equation lies in the fact that it takes into account the compensation C 01 and C 02 ( Figure 1) and at the same time linearizes the quartz characteristics due to the ∆C x change ( Figure 1) and allows for the sensitivity setting [6,7,22] ( ) ( ) ( )…”

“…It also compensates the temperature-frequency characteristics of two quartz crystals, enabling very stable transducer functioning in an extended temperature range. In addition, it also compensates the influence of any other electronic circuit element, and foresees the functioning of the sensitive capacitive element (in case reactances are capacitive) [4][5][6][7]. Temperature-wise, the new method makes possible a stable functioning of the small reactance conversion to a frequency signal with a small number of elements in a transducer.…”

“…Frequency sensitivity in (12) and (14) can be set with the value k [6], achieving at the same time simultaneous dependence linearization ∆f 0 (C o1 + C o1 + ∆C x ) [6,21,22,36]. At every switch between Sw signals, the frequency f out is measured synchronously by the counter (Figure 3) [23] and its value is transferred to the LabVIEW software calculating the difference between the two frequencies.…”