Phase lock loop having temperature drift compensation and method thereof

Abstract

The invention relates to a phase lock loop with excursion expiation of temperature and a method thereof. The loop is added with a voltage reference generating circuit, a comparator, and a digital logic control circuit. Two magnitude of voltage generated by the voltage reference generating circuit is taken as two endpoint values of the effective range of the control voltage of the phase lock loop. The control voltage of the phase lock loop is compared with the two magnitude of voltage. When the control voltage falls in the effective range, the output of the digital logic control circuit keeps constant. When the control voltage falls over the effective range, the digital logical control unit calculates and selects a capacitance wire again to cause that the control voltage falls in the effective range, thus avoiding the occurrence of unlocking.

Description

technical field [0001] The invention belongs to the field of signal processing, and relates to a phase-locked loop and a method for generating accurate and stable frequency output used in communication and information processing systems. Background technique [0002] In a wireless communication system, it is required to generate a high-performance local oscillator signal in the radio frequency band for the mixer to perform up / down conversion operation. Therefore, being able to output a stable clock under various environmental conditions is the primary requirement for the phase-locked loop. A typical phase-locked loop structure is as figure 1 Shown, including frequency and phase detector, charge pump, loop filter, voltage-controlled oscillator VCO, N frequency divider. A typical VCO such as figure 2 As shown, the LC resonant network is composed of inductors, switched capacitor arrays, and varactors. Digital calibration generates the control word of the switched capacitor ...

AI Technical Summary

Problems solved by technology

When the PLL is locked at the set frequency, the control word of the switched capacitor array is selected, and a VCO capacitor line is selected correspondingly, and the VCO control voltage is Vtune. If Vtune falls within the effective range of the VCO control voltage on the current capacitor line Once the temperature changes, the VCO oscillation frequency will drift, and Vtune needs to change accordingly to maintain the closed-loop lock. However, the limited adjustment range of the control voltage Vtune on the current capacitance line can easily lead to loss of lock, such as image 3 shown

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