Numerically controlled oscillator with high tuning precision

Abstract

The invention discloses an inductance-capacitance type numerically controlled oscillator with high tuning precision. A resonant circuit comprises an inductor L, a capacitor C, a first control unit circuit, ..., and a nth control unit circuit, wherein the first control unit circuit is controlled by a first control bit D1 and consists of P type field effect transistors PM11, PM12, PM13 and PM14, the nth control unit circuit is controlled by a nth control bit Dn and consists of P type field effect transistors PMn1, PMn2, PMn3 and PMn4, and the inductor L, the capacitor C, the first control unit circuit, ..., and the nth control unit circuit are connected in parallel to form a control unit array; a first input end of the capacitor L is connected with a first input end of the capacitor C to be taken as a first input end (1) of the resonant circuit, and a second input end of the inductor L is connected with a second input end of the capacitor C to be taken as a second input end (2) of the resonant circuit; and each control unit is formed by the reverse parallel connection of PMOS (Positive Channel Metal Oxide Semiconductor) tube pairs with different sizes, the small capacitance difference can be obtained by the size difference of the PMOS tubes, and the fine frequency tuning step can be obtained, namely, the high frequency tuning precision is realized.

Description

technical field [0001] The invention relates to a numerically controlled oscillator, which introduces a novel switch PMOS capacitor unit to obtain a small unit switch capacitor, so as to realize fine frequency tuning steps, that is, high frequency tuning accuracy. Background technique [0002] The numerically controlled oscillator can be regarded as a digital-to-frequency conversion device. It is controlled by the input digital signal and can generate an oscillation signal whose frequency corresponds to the input control word. It is one of the most important modules in the digital phase-locked loop. Through the phase-locked loop The loop feedback control produces a frequency-phase stable output signal, which provides a reference clock or a local oscillator signal for the electronic system. The frequency tuning accuracy of the NC oscillator is one of the key indicators, which often determines its application occasions. At the same time, higher frequency tuning accuracy is als...

AI Technical Summary

Problems solved by technology

Therefore, the unit switching capacitance is the difference between the strong inversion capacitance and the depletion region capacitance, which is limited by the characteristic size of the process, and the capacitance value is usually large, which leads to limited tuning accuracy of the numerical control oscillator, that is, a large tuning step size

This limits the application of the inductor-capacitor numerically controlled oscillator to a certain extent.

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