Method to compensate the VCO buffer Q factor at low frequency band
OwnerQiang Liinventor
Life of this patent
Estimating the term…
Abstract
A voltage control oscillator (VCO) buffer for a local oscillator (LO) generator system of a phase locked loop (PLL) in a transceiver chip. The VCO buffer includes a capacitor bank, a VCO buffer core and a current stirring unit. The VCO buffer core receives an input signal, and outputs an output signal. The input signal and the output signal have substantially the same frequency. A capacitance of the capacitor bank and a magnitude of a current supplied by the current stirring unit are variable depending on a frequency of the input signal.
Claims20
A voltage controlled oscillator (VCO) buffer for a local oscillator (LO) generator system, the VCO buffer comprising:
- a VCO buffer core for receiving an input signal having a frequency and for outputting an output signal;
- a capacitor bank coupled to the VCO buffer core, the capacitor bank having a capacitance which is variable;
- and
- a current stirring unit coupled to the VCO buffer core, and for providing a current to the VCO buffer core,
- wherein the capacitance of the capacitor bank and a magnitude of the current provided by the current stirring unit are variable depending on the frequency of the input signal.
A local oscillator (LO) generator system comprising:
- a voltage controlled oscillator (VCO) for receiving a control signal and for generating an oscillation signal having a frequency which depends on the control signal;
- a VCO buffer comprising:
- a VCO buffer core for receiving the oscillation signal as an input signal and for outputting an output signal;
- a capacitor bank coupled to the VCO buffer core, the capacitor bank having a capacitance which is variable;
- and
- a current stirring unit coupled to the VCO buffer core, and for providing a current to the VCO buffer core,
- wherein the capacitance of the capacitor bank and a magnitude of the current provided by the current stirring unit are variable depending on the frequency of the input signal;
- and
- at least one divider for receiving the output signal, and for generating a divided output signal.
In a voltage controlled oscillator (VCO) buffer of a local oscillator (LO) generator system, the VCO buffer for receiving an input signal and for outputting an output signal, and having a buffer core, a capacitor bank and a current stirring unit, a method of compensating for de-Q-ing at a low frequency band comprising:
- increasing a magnitude of a current provided by the current stirring unit as a frequency of the input signal to the VCO buffer decreases;
- and
- decreasing the magnitude of the current provided by the current stirring unit as the frequency of the input signal to the VCO buffer increases.
Dependencies are inferred from the claim text.