Freescale Semiconductor,inc.

Devesh P Singh

Anand Kumar Sinha

Sanjay Kumar Wadhwa

Firas Najeh Abughazaleh

Krishna Thakur

Deependra Kumar Jain

Avinash Chandra Tripathi

A charge pump includes a charge pump core circuit, a replica bias circuit, and a differential amplifier. The charge pump core circuit includes current source and sink circuits for charging and discharging an output node of the charge pump core circuit. The current source and current sink circuits are user programmable using bit signals to adjust a bandwidth and a phase margin of a phase-locked loop (PLL) that includes the charge pump. An impedance of the replica bias circuit varies based on the bit signals. The differential amplifier and the replica bias circuit form a feedback loop that reduces current mismatch between the current source and sink circuits.

Programmable charge pump

A phase-locked loop (PLL) for generating an oscillating signal includes a frequency bounding circuit. When a frequency of the oscillating signal is greater than a first threshold value, which is greater than a maximum normal operational frequency of the PLL, the frequency bounding circuit forces a charge pump to discharge a loop filter until the oscillating signal frequency is less than a second threshold value that is within the normal operational frequency range of the PLL. When the frequency of the oscillating signal is less than a third threshold value, which is less than a minimum normal operational frequency of the PLL, the frequency bounding circuit forces the charge pump to charge the loop filter until the oscillating signal frequency is greater than a fourth threshold value that is within the normal operational frequency range of the PLL.

Phase-locked loop with frequency bounding circuit

A buffer circuit includes an inverter and a level-shifter. The inverter receives a first oscillating signal at a first voltage level and generates an inverted version of the first oscillating signal at a second voltage level. The level-shifter receives a second oscillating signal at a third voltage level, which has a phase difference from the first oscillating signal, and the inverted first oscillating signal, and generates a buffer output signal at a fourth voltage level.

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Bijnor, India

Devesh P Singh