In this Quartz Resonators series video, we’ll look at Series and Parallel Resonance Modes.

All quartz crystal resonators have a Series & Parallel resonant frequency. This is the Frequency that offers the least amount of impedance to resonation. At this resonant frequency, the crystal appears completely resistive in the circuit.

Let’s discuss the Series Resonance Mode

In a series L-C circuit the frequency at which the reactance of the inductance and the capacitance cancel each other out, is the resonant frequency.

Characteristics of a series resonance circuit include:

  • Minimum impedance
  • and Maximum circuit current

Next, let’s look at the Parallel Resonance Mode

In a parallel circuit having resistance, inductance and capacitance a parallel resonance (also referred to as anti-resonance) will be achieved. When the resultant current through this parallel combination is in phase with the supply voltage, the parallel resonant circuit will store energy in the magnetic field of the inductor and the electric field of the capacitor. This energy is constantly being transferred back and forth between the inductor and the capacitor which results in a zero current or energy being drawn from the supply.

Characteristics of a parallel resonance circuit include:

  • Maximum impedance
  • and Minimum circuit current

Lastly, I want to cover Adjusting Frequency, reffered to as “Pulling”

Crystals can be “pulled” from this series frequency by adding capacitive reactance in series with the crystal. When operating in combination with an external load capacitance the crystal oscillates in a frequency range slightly above its series resonant frequency. This is the parallel or load resonant frequency. When ordering a parallel crystal, always specify the nominal parallel resonant frequency and specify the circuit load capacitance in Pico Farads.

Watch the above video to learn more about Series & Parallel Resonance Modes then click on the button below to start searching for the exact part you need!




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Series & Parallel Resonance Modes was last modified: June 30th, 2022 by ECS Inc.