High-integration-level active dynamic loop filter

Abstract

The invention relates to a high-integration-level active dynamic loop filter, which comprises an integration path, a proportion path, a first integration capacitor, a second integration capacitor and an operational amplifier, and is characterized in that the filter adopts a double-ring structure of a separated charge pump, a switch capacitor is used for replacing a resistor, the precision is better, and the thermal noise of the resistor is reduced; and the sampling reset loop filter generates a constant current with a proper proportion during the whole input updating period instead of generating a large-proportion current during the input phase difference period, so that a more stable control current is obtained, and burrs and overshoot are reduced. And meanwhile, the double-sampling capacitor structure has higher power supply and substrate noise suppression capability, so that better jitter performance is generated. The sampling reset switch capacitor and the annular dynamic amplifier are adopted, so that the whole filter can be realized under low voltage, and the current matching of the charge pump becomes possible.

Description

technical field [0001] The invention belongs to the technical field of filters, in particular to a highly integrated active dynamic loop filter. Background technique [0002] For active loop filter applications that work at ultra-low voltage and require small area and high integration, the phase-locked loop frequency synthesizer circuit directly affects the performance of the wireless transceiver, and the loop filter is an important part of the frequency synthesizer. The module itself has the functions of time-domain integration and frequency-domain low-pass filtering, which can filter out the clutter components in the comparison voltage output by the phase detector. Adjusting the parameters of the loop filter can control the performance of the entire phase-locked loop, so the quality of its design determines the phase noise, spurious and frequency hopping time of the system and other important indicators. great contribution. [0003] The loop filter is divided into two ty...

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Problems solved by technology

But this structure also has the disadvantages of traditional filters. First, this structure still generates a large proportion of current during the input phase difference, which leads to large glitches and overshoots in the oscillator control current.

In addition, it is difficult to ensure a good match of the charge pump current at low voltage, and at the same time it will greatly compress the VCO input voltage V CTRL

The mismatch current of the charge pump is the most important performance index of the charge pump. Excessive current mismatch will seriously affect the noise performance and even the function of the phase-locked loop. At the same time, V CTRL The compression requires a larger KVCO, which will also make the noise performance worse. In addition, the resistor R 1 thermal noise

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