A Temperature-Drift Suppressed Charge Pump for CPPLL Applied in MEMS Oscillator

In the extreme working environment such as aerospace, PLL applied in microelectromechanical systems (MEMS) oscillator need a temperature-stable operating state which keeps overall electronic system in working. However, a key unit of PLL to maintain its performance is an invulnerable charge pump (CP) structure in wide temperature range. However, the working current of the CP in charge pump phase-locked loop (CPPLL) becomes unstable with the change of temperature and deteriorates the stray performance and interferes with the locking function. To stabilize the current output of the CP at different temperatures and to guarantee the stray performance of the system, in new CP structure proposed in this paper, the current of the CP is compensated and the current matching is enhanced by introducing a temperature compensation circuit. The circuit simulation result based on 180nm CMOS technology show that the output current of the pump can be basically stable at 100μA in the range of -40~175°C, the temperature coefficient of the current is 16.43ppm/°C, the matching range of the current is 0.4~3.1V, and the loss ratio is less than 0.5%.