Low current mismatch charge pump circuit for resisting process fluctuation under low voltage of phase lock loop

Abstract

The invention discloses a low current mismatch charge pump circuit for resisting process fluctuation under low voltage of a phase lock loop. The low current mismatch charge pump circuit for resisting the process fluctuation under the low voltage of the phase lock loop comprises a current mirror composed of PMOS devices P1, P2, P3 and P4 and NMOS devices N1, N2 and N3, a charging circuit composed of PMOS devices P5 and P6 and a transmission gate T1, a discharging circuit composed of NMOS devices N4 and N5 and a transmission gate T2, a feedback circuit composed of PMOS devices P7 and P8 and NMOS devices N6 and N7, and a body bias circuit composed of a PMOS device P9, an NMOS device N8 and polycrystalline silicon resistors R1 and R2. The low current mismatch charge pump circuit for resisting the process fluctuation under the low voltage of the phase lock loop can guarantee a voltage output range of a charge pump under low power supply voltage by controlling grid electrodes of charging and discharging current pipes through the transmission gates. The low current mismatch charge pump circuit for resisting the process fluctuation under the low voltage of the phase lock loop performs feedback regulation through MOS pipes different in threshold value, guarantees good match of charging and discharging currents, introduces the body bias circuit, and reduces influences from fluctuation of process corners on 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...

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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 devia...

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