US 12,113,480 B2
Crystal oscillator and method for performing startup of crystal oscillator
Chien-Wei Chen, Hsinchu (TW); Chao-Ching Hung, Hsinchu (TW); and Yu-Li Hsueh, Hsinchu (TW)
Assigned to MEDIATEK INC., Hsin-Chu (TW)
Filed by MEDIATEK INC., Hsin-Chu (TW)
Filed on Feb. 24, 2023, as Appl. No. 18/113,623.
Claims priority of provisional application 63/368,999, filed on Jul. 21, 2022.
Prior Publication US 2024/0030872 A1, Jan. 25, 2024
Int. Cl. H03B 5/36 (2006.01); H03B 5/04 (2006.01); H03B 5/12 (2006.01)
CPC H03B 5/366 (2013.01) [H03B 5/04 (2013.01); H03B 5/1265 (2013.01); H03B 2200/0094 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A crystal oscillator (XO), comprising:
a XO core circuit, configured to generate a XO signal;
an auxiliary oscillator, configured to generate an auxiliary signal; and
a frequency detection circuit, comprising a resistive circuit, wherein the frequency detection circuit is configured to generate a detection voltage according to a driving signal associated with the auxiliary signal and a first impedance of the resistive circuit;
wherein:
during a first phase of the XO, the auxiliary oscillator is calibrated by utilizing the XO signal as a reference signal, and the resistive circuit is calibrated by controlling the first impedance to make the detection voltage approach a reference voltage according to a comparison result of the detection voltage and the reference voltage; and
during a second phase of the XO, the auxiliary oscillator is calibrated to make a frequency of the driving signal to be a driving frequency which makes the detection voltage approach the reference voltage according to the comparison result of the detection voltage and the reference voltage, and the driving signal having the driving frequency is injected to the XO core circuit for accelerating the startup of the XO core circuit.