Rapidly-locked frequency generator

Abstract

The invention provides a frequency generator for quick locking, which comprises a phase frequency detector, a charge pump, a filter, a voltage controlled oscillator and a first locking unit connected with the charge pump and the filter. When no phase difference is existed between reference clock signal and feedback clock signal, the first locking unit outputs a quick locking signal of decreasing charge-discharge current of the charge pump and increasing resistance of the filter. The frequency generator can shorten locking time of frequency and phase.

Description

technical field [0001] The invention relates to the technical field of communication, in particular to a frequency generator for fast locking. Background technique [0002] In wireless communication systems, frequency generators are used to provide accurate and stable clock signals. In order to obtain a high-precision clock signal, a quartz crystal oscillator is usually used, but the frequency of the quartz crystal oscillator is not easy to change, so it cannot be applied to a communication system with multiple channel frequencies, and a phase-locked loop (PLL, Phase Lock Loop), Frequency synthesis techniques such as frequency multiplication and frequency division can obtain multi-frequency, high-stable clock signal output. As described in the Chinese invention patent with the patent number ZL03102743.1, inserting A frequency divider (Divider) can constitute a frequency generator. [0003] The circuit of a kind of frequency generator is as shown in Figure 1, comprises fre...

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Problems solved by technology

However, in a wireless communication system, according to the channel spacing requirements, the clock signal CLKOUT output by the frequency generator must have high precision, and the reference clock signal REFCLK needs to have a very low frequency, and accordingly, the bandwidth of the phase-locked loop will be very narrow. , the locking time of the frequency generator will be very slow, which is difficult to meet the high processing speed requirements of the wireless communication system

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