Oscillating device
An oscillating device includes a first quartz crystal resonator, a driving circuit, a first buffer, a bandpass filter, a second quartz crystal resonator, and a second buffer coupled to each other. The driving circuit drives the first quartz crystal resonator to generate a first oscillating signal with a resonant frequency. The first buffer isolates from a load variation to generate a first clock signal in response to the first oscillating signal. The bandpass filter allows only the first clock signal with the harmonic frequency of the resonant frequency within a passband to pass through, thereby generating a filtered signal. The second quartz crystal resonator rectifies the filtered signal to generate a second oscillating signal having the harmonic frequency. The second buffer isolates from a load variation to generate a second clock signal in response to the second oscillating signal.
1 . An oscillating device comprising:
a first quartz crystal resonator having a resonant frequency;
a driving circuit coupled to the first quartz crystal resonator and configured to drive the first quartz crystal resonator to generate a first oscillating signal with the resonant frequency;
a first buffer coupled to the driving circuit and configured to receive the first oscillating signal and isolate from a load variation behind the first quartz crystal resonator and the driving circuit to generate a first clock signal in response to the first oscillating signal;
a bandpass filter, coupled to the first buffer, having a passband, wherein the bandpass filter is configured to receive and allow only the first clock signal with a harmonic frequency of the resonant frequency within the passband to pass through, thereby generating a filtered signal;
a second quartz crystal resonator, having a frequency equal to the harmonic frequency, coupled to the bandpass filter and configured to receive the filtered signal to generate a second oscillating signal having the harmonic frequency; and
a second buffer coupled to the second quartz crystal resonator and configured to receive the second oscillating signal and isolate from a load variation behind the first quartz crystal resonator, the driving circuit, the first buffer, the bandpass filter, and the second quartz crystal resonator to generate a second clock signal in response to the second oscillating signal.
2 . The oscillating device according to claim 1 , further comprising a waveform adjustment circuit coupled between the bandpass filter and the second quartz crystal resonator and configured to adjust a waveform swing, a direct-current (DC) level, or both of the filtered signal, and to transmit the adjusted filtered signal to the second quartz crystal resonator.
3 . The oscillating device according to claim 2 , wherein the driving circuit, the first buffer, the bandpass filter, and the waveform adjustment circuit are integrated into an integrated circuit (IC), and the IC and the first quartz crystal resonator are coupled into a Crystal Oscillator (XO), a Temperature Compensated Crystal Oscillator (TCXO), a Voltage Controlled Crystal Oscillator (VCXO), an Oven Controlled Crystal Oscillator (OCXO), a Voltage Controlled Temperature Compensated Crystal Oscillator (VCTCXO), or a Voltage Controlled Oven Controlled Crystal Oscillator (VCOCXO).
4 . The oscillating device according to claim 2 , wherein the driving circuit, the first buffer, the bandpass filter, the waveform adjustment circuit, and the second buffer are integrated into an integrated circuit (IC), and the IC and the first quartz crystal resonator are coupled into a Crystal Oscillator (XO), a Temperature Compensated Crystal Oscillator (TCXO), a Voltage Controlled Crystal Oscillator (VCXO), an Oven Controlled Crystal Oscillator (OCXO), a Voltage Controlled Temperature Compensated Crystal Oscillator (VCTCXO), or a Voltage Controlled Oven Controlled Crystal Oscillator (VCOCXO).
5 . The oscillating device according to claim 2 , wherein the driving circuit and the first buffer are integrated into a first integrated circuit (IC), and the first IC and the first quartz crystal resonator are coupled into a crystal oscillator (XO), a Temperature Compensated Crystal Oscillator (TCXO), a Voltage Controlled Crystal Oscillator (VCXO), an Oven Controlled Crystal Oscillator (OCXO), a Voltage Controlled Temperature Compensated Crystal Oscillator (VCTCXO), or a Voltage Controlled Oven Controlled Crystal Oscillator (VCOCXO).
6 . The oscillating device according to claim 5 , wherein the bandpass filter and the waveform adjustment circuit are integrated into a second integrated circuit (IC).
7 . The oscillating device according to claim 5 , wherein the bandpass filter, the waveform adjustment circuit, and the second buffer are integrated into a second integrated circuit (IC).
8 . The oscillating device according to claim 2 , wherein the driving circuit, the first buffer, and the bandpass filter are integrated into an integrated circuit (IC), and the IC and the first quartz crystal resonator are coupled into a Crystal Oscillator (XO), a Temperature Compensated Crystal Oscillator (TCXO), a Voltage Controlled Crystal Oscillator (VCXO), an Oven Controlled Crystal Oscillator (OCXO), a Voltage Controlled Temperature Compensated Crystal Oscillator (VCTCXO), or a Voltage Controlled Oven Controlled Crystal Oscillator (VCOCXO).
9 . The oscillating device according to claim 1 , wherein the bandpass filter is configured to adjust the passband and a central frequency equal to the harmonic frequency.