Frequency band scanning circuit for LC type phase locked loop

Abstract

The invention relates to a frequency band scanning circuit for an LC type phase locked loop. The frequency band scanning circuit comprises a comparator, an AND gate circuit, an N-bit counter, and a D trigger. The input end of the comparator is connected to lower limit voltage VL and a determination voltage Vdect. The input end of the AND gate circuit is connected to a counting circuit Count_clk and the output end of the comparator. The D input end of the D trigger is connected to the output end O of the N-bit counter. The input end C of the N-bit counter is connected to a counting period Count_period. The C input end of the D trigger is connected to the output end of the AND gate circuit. The Q output end of the D trigger is connected to a VCOsel selection signal and is used for controlling a voltage controlled oscillator array SW<0:2<N>-1>. According to the frequency band scanning circuit, the determining voltage is judged by using the feedback circuit of the phase-locked loop, the configuration circuit and process are simplified greatly, the automatic frequency band scanning and selection of the voltage controlled oscillator array can be realized, and the frequency band scanning circuit can be widely applied to the design of the LC type phase-locked loop.

Description

technical field [0001] The invention belongs to the technical field of microelectronics, and relates to an LC phase-locked loop, in particular to a frequency band scanning circuit for the LC phase-locked loop. Background technique [0002] As a common component, the phase-locked loop is used in digital frequency synthesis, wireless transceiver and other fields, and its performance directly affects the working quality of the entire circuit system. Under high-frequency working conditions, LC phase-locked loops are widely used in the field of wireless communication due to their superior phase noise performance and frequency stability. Due to the narrow frequency band of a single-sized LC oscillator, in practical applications, it is necessary to combine LCs of different sizes into an array application to meet the broadband requirements. The traditional method calculates the output frequency based on the input reference frequency and multiplier, and then selects the LC array bas...

AI Technical Summary

Problems solved by technology

The traditional method calculates the output frequency based on the input reference frequency and multiplier, and then selects the LC array based on the operating temperature. The calculation process and configuration are cumbersome

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