A charge pump applied to a frequency synthesizer

A frequency synthesizer and charge pump technology, applied in the field of phase-locked loops, can solve the problems of current mismatch of charge and discharge current changes, poor spurious performance of frequency synthesizers, and decrease in linearity of charge pump, so as to suppress charge redistribution. , Eliminate clock feedthrough effect, reduce the effect of mismatch

Active Publication Date: 2019-06-25
SOUTHEAST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, provide a charge pump applied to a frequency synthesizer, and solve the problem that the output voltage of the charge pum

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  • A charge pump applied to a frequency synthesizer
  • A charge pump applied to a frequency synthesizer
  • A charge pump applied to a frequency synthesizer

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Embodiment Construction

[0017] Embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0018] like figure 2 As shown, the present invention designs a charge pump applied to a frequency synthesizer, including a charging and discharging current branch 1 and an output impedance multiplication circuit 2; wherein, the charging and discharging current branch 1 is composed of complementary CMOS switches, rail-to-rail The unit negative feedback loop and current source composed of input and output amplifiers use an improved drain-side switch charge pump structure to charge and discharge the output node, and eliminate clock feedthrough by using complementary CMOS switches instead of ordinary single-tube MOS switches. Effect, use the unity gain amplifier A1 composed of rail-to-rail op amp to eliminate the charge sharing effect, reduce the influence of the clock feedthrough effect, suppress the parasitic capacitance of the current source drain and the charge ...

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Abstract

The invention discloses a charge pump applied to a frequency synthesizer. The charge pump comprises a charge-discharge current branch and an output impedance multiplication circuit. The charging and discharging current branch is composed of a unit negative feedback loop and a current source, wherein the unit negative feedback loop is composed of a complementary CMOS switch and a rail-to-rail inputand output amplifier, and the charging and discharging current branch is used for charging and discharging an output node and eliminating a clock feed-through effect and a charge sharing effect. Theoutput impedance multiplication circuit is composed of a folding type cascode structure and is used for improving the output impedance of the charge pump. The output impedance multiplication circuit comprises a reference current source, first, second, third, fourth, fifth, seventh, eighth, tenth, eleventh and sixteenth NMOS tubes, and first, second, third, fourth, sixth, seventh, ninth, tenth andfifteenth PMOS tubes. The invention is suitable for the drain terminal switch charge pump with good matching characteristic under low voltage, improves the matching degree of charging and dischargingcurrent, improves the phase noise of the frequency synthesizer, and improves the output impedance of the charge pump.

Description

technical field [0001] The invention relates to a charge pump applied to a frequency synthesizer, belonging to the technical field of phase-locked loops. Background technique [0002] A frequency synthesizer is a technology that uses the principle of feedback control to achieve frequency and phase synchronization. It generally has five components, a frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator, and a frequency divider. As an important part of the frequency synthesizer, the pump is a hot topic in the research of analog integrated circuits. figure 2 The performance of the conventional charge pump shown is affected by non-ideal factors such as current mismatch, charge sharing, and clock feedthrough, where the current mismatch of the charge pump will cause spurs in the output of the frequency synthesizer, thereby constraining the frequency synthesizer. Therefore, designing a charge pump with high linearity and reducing the mismatch between t...

Claims

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Application Information

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IPC IPC(8): H03L7/089
Inventor 吴建辉何凯陈超李红
Owner SOUTHEAST UNIV
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