Invention Grant
- Patent Title: Phase lock loop with a digital charge pump
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Application No.: US15443217Application Date: 2017-02-27
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Publication No.: US09948312B2Publication Date: 2018-04-17
- Inventor: Jayawardan Janardhanan , Krishnaswamy Thiagarajan , Jagdish Chand Goyal
- Applicant: TEXAS INSTRUMENTS INCORPORATED
- Applicant Address: US TX Dallas
- Assignee: TEXAS INSTRUMENTS INCORPORATED
- Current Assignee: TEXAS INSTRUMENTS INCORPORATED
- Current Assignee Address: US TX Dallas
- Agent John R. Pessetto; Charles A. Brill; Frank D. Cimino
- Priority: IN201641007438 20160229
- Main IPC: H03L7/087
- IPC: H03L7/087 ; H03L7/06 ; H03L7/00 ; H03L7/08 ; H03L7/089

Abstract:
A phase lock loop (PLL) includes a voltage-controlled oscillator (VCO) and a frequency detector to generate a FAST signal responsive to a frequency of a reference signal being greater than the frequency of a feedback signal derived from the VCO and to generate a SLOW signal responsive to the frequency of the reference signal being smaller than the frequency of the feedback signal. The PLL also includes a digital charge pump, a loop filter, and a state machine circuit. Responsive to receipt of multiple consecutive FAST signals when the digital charge pump is providing a charging current to the loop filter, the state machine circuit reconfigures the digital charge pump to increase the charging current to the loop filter. Responsive to receipt of multiple consecutive SLOW signals when the loop filter is discharging, the state machine circuit reconfigures the digital charge pump to cause the loop filter's discharge current to increase. Upon detection of a terminal condition, the state machine circuit may disable the digital charge pump and enable operation of an analog charge pump.
Public/Granted literature
- US20170250693A1 PHASE LOCK LOOP WITH A DIGITAL CHARGE PUMP Public/Granted day:2017-08-31
Information query
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