Low Current Mismatch Charge Pump Circuit for Resisting Process Fluctuation at Low Voltage of Phase Locked Loop

Abstract

The invention discloses a low-current mismatch charge pump circuit used for resisting technological fluctuations under low voltage of a phase-locked loop. The charge pump circuit includes: a current mirror composed of PMOS devices P1, P2, P3, P4 and NMOS devices N1, N2, N3; a charging circuit composed of PMOS devices P5, P6 and transmission gate T1; a charging circuit composed of NMOS devices N4, N5 and the discharge circuit composed of transmission gate T2; the feedback circuit composed of PMOS devices P7, P8 and NMOS devices N6, N7; and the body bias circuit composed of PMOS device P9, NMOS device N8 and polysilicon resistors R1, R2. The gate of the charging and discharging current tube is controlled by the transmission gate to ensure the voltage output range of the charge pump under low power supply voltage. Feedback regulation is performed through MOS tubes with two different thresholds, high and low, to ensure a good match between charge and discharge currents. A body bias circuit is introduced to reduce the impact of process angle fluctuations on the performance of the charge pump.

Description

technical field [0001] The invention relates to the field of integrated circuit design, in particular to a low-current-mismatch charge-pump circuit used in a phase-locked loop to resist process fluctuations at low voltage. Background technique [0002] As the most popular frequency synthesizer structure in modern wireless communication system applications, phase-locked loop (PLL) can complete signal modulation and demodulation, clock recovery, and generate local oscillator for mixer and carrier recovery of wireless receiver Signal. The charge pump phase-locked loop (CP-PLL) has become the most common phase-locked loop circuit because of its high speed and low noise. The charge pump (CP) circuit plays a very important role in the charge pump phase-locked loop. Its main function is to pass the UP and DN pulse digital signals from the phase frequency detector (PFD) through the low-pass filter (LPF) Converted to an analog voltage signal, the signal controls the oscillation fre...

AI Technical Summary

Problems solved by technology

However, if it is placed at the gate terminal, the turn-on and turn-off time of charge pump charging and discharging will increase due to the gate capacitance of the current tube, and the output impedance of the charge pump is small, which is easily affected by the output voltage, resulting in current mismatch.

[0008] In addition, when considering the process deviation in the integrated circuit manufacturing process, the mismatch between the charging current and the discharging current of the traditional charge pump circuit will be amplified again

[0009] To sum up, under low voltage operation, it is difficult for the traditional charge pump circuit to obtain a wide output voltage range and low mismatch charge and discharge current

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