18990415. SYSTEMS AND METHODS FOR IMPROVED CHARGE PUMP PHASE-LOCKED LOOP PHASE STABILITY (Apple Inc.)
SYSTEMS AND METHODS FOR IMPROVED CHARGE PUMP PHASE-LOCKED LOOP PHASE STABILITY
Organization Name
Inventor(s)
Hongrui Wang of San Jose CA US
Abbas Komijani of Mountain View CA US
Hideya Oshima of Santa Clara CA US
Reetika K Agarwal of San Jose CA US
SYSTEMS AND METHODS FOR IMPROVED CHARGE PUMP PHASE-LOCKED LOOP PHASE STABILITY
This abstract first appeared for US patent application 18990415 titled 'SYSTEMS AND METHODS FOR IMPROVED CHARGE PUMP PHASE-LOCKED LOOP PHASE STABILITY
Original Abstract Submitted
In a charge pump-based PLL circuit, charge pump output current variation may cause phase instability at an output of a VCO. The output current variation may be caused by low-frequency disturbances (e.g., tuning voltage (Vtune) drift with channel length modulation effect), disturbance in a gate bias voltage of a transistor, or a VDD transient. Such a low-frequency disturbance may occur during initial lock, which may affect phase settling time, or after lock, which may result in phase instability. A replica charge pump and a current filtering and compensation circuit may be implemented at the output of a main charge pump to provide error current compensation to suppress channel length modulation effect, improve phase stability, and reduce phase noise.
