Quartz Crystal Oscillator: Series and Parallel Resonant Frequencies

The correct answer is option 'C', which states that a quartz crystal oscillator consists of both series and parallel resonant frequencies. In order to understand this, let's break down the concept of a quartz crystal oscillator and its resonant frequencies.

What is a Quartz Crystal Oscillator?
A quartz crystal oscillator is an electronic circuit that uses the mechanical resonance of a quartz crystal to generate a stable frequency signal. It is commonly used in various electronic devices, such as watches, radios, computers, and communication systems, due to its high accuracy and stability.

Series Resonant Frequency:
The series resonant frequency is the natural frequency at which a system oscillates when the inductive and capacitive reactance in the circuit cancels out, resulting in a minimum impedance. In the case of a quartz crystal oscillator, the quartz crystal is connected in series with a feedback loop. When the frequency of the applied voltage matches the series resonant frequency of the crystal, it starts to oscillate and generate a stable output signal.

Parallel Resonant Frequency:
The parallel resonant frequency, on the other hand, is the natural frequency at which a system oscillates when the capacitive and inductive reactance in the circuit cancel out, resulting in a maximum impedance. In a quartz crystal oscillator, the quartz crystal is also connected in parallel with a load capacitor. When the frequency of the applied voltage matches the parallel resonant frequency of the crystal, it starts to oscillate and generate a stable output signal.

Combining Series and Parallel Resonant Frequencies:
In a quartz crystal oscillator, both the series and parallel resonant frequencies are utilized to ensure stable and accurate oscillations. The series resonant frequency provides a high degree of stability, while the parallel resonant frequency determines the overall frequency response of the oscillator.

The series resonant frequency is typically higher than the parallel resonant frequency. Therefore, the crystal operates in the series resonant mode, which provides a high-quality factor (Q factor) and stable output frequency. The parallel resonant frequency is used to adjust the frequency of the crystal oscillator by varying the load capacitance.

In Conclusion:
A quartz crystal oscillator consists of both series and parallel resonant frequencies. The series resonant frequency is used for stable oscillations, while the parallel resonant frequency is used for frequency adjustment. By utilizing both resonant frequencies, a quartz crystal oscillator can provide accurate and stable frequency signals, making it a crucial component in various electronic devices.