Circulation circuit voltage-controlled oscillator with temperature compensation effect

Abstract

The invention relates to a loop voltage controlled oscillator with temperature compensation effect, which is composed of N delay units with temperature compensation connected in a ring and a temperature compensation circuit. The delay unit is an ordinary inverter On the basis of the load tube, one or more MOS tubes are connected in parallel on the load tube, so that it is controlled by the temperature compensation voltage to adjust the conduction degree, thereby compensating the frequency change caused by the temperature change. Its temperature compensation circuit is composed of a temperature sensor and a voltage amplifier, the temperature sensor is composed of a diode, and the amplification factor of the voltage amplifier is controlled by the external voltage Vc of the voltage-controlled oscillator, so that the output frequency of the voltage-controlled oscillator is different under different Vc Corresponding temperature compensation can be obtained to keep the same as before the temperature did not change. The loop voltage controlled oscillator of the present invention is particularly suitable for a phase-locked loop with digital preset or digital coarse adjustment.

Description

technical field [0001] The invention relates to the technical field of phase-locked loops used in communication and information processing systems, in particular to the design of loop voltage-controlled oscillators. technical background [0002] The voltage-controlled oscillator (VCO) is the most important component of the phase-locked loop (PLL). In order to obtain a high-frequency, high-precision output signal frequency, the form of an LC voltage-controlled oscillator or a loop voltage-controlled oscillator is generally used. . Loop voltage-controlled oscillators have been widely used in communication and digital circuits due to their advantages of low power consumption, wide output frequency range, and small chip area. [0003] The loop voltage controlled oscillator is composed of N delay units connected in a ring, and the delay units can be single-ended or differential. For a single-ended delay unit, N can only be an odd number greater than or equal to 3; for a differe...

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Problems solved by technology

However, the greater the VCO gain, the more susceptible to external interference, which is not conducive to improving the phase noise of the phase-locked loop, and phase noise is the most important indicator of the phase-locked loop

Secondly, the larger the VCO gain, the larger the capacitance of the loop filter will be, which is not conducive to circuit integration.

[0005] For a VCO with digital coarse adjustment or digital preset, the VCO gain is generally relatively small, about tens of MHz / V, so the frequency drift with temperature will seriously affect whether the phase-locked loop can work normally

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