A kind of sigma-delta modulator and a kind of operation method for sigma-delta modulator

Abstract

The invention discloses a Sigma-Delta modulator and an operation method for the Sigma-Delta modulator. The Sigma-Delta modulator and the operation method are used for receiving input of a fractional part control word and output coupled to a corresponding frequency divider, and respond to the input fractional part control word to be used for controlling the frequency dividing ratio of the frequency divider; the Sigma-Delta modulator comprises n modulator bodies, a quantizer and an integer summator, wherein the n modulator bodies, the quantizer and the integer summator are sequentially connected in a cascaded mode, and the n is a positive integer lager than or equal to two; the n modulator bodies include previous n-1 previous-(n-1)-stage modulator bodies and the nth modulator body, and the previous-(n-1)-stage modulator bodies at least include the first-stage modulator body. The Sigma-Delta modulator has the advantages that the high order is achieved, the complexity and the power dissipation of circuit implementation are effectively reduced on the premise that the noise restraining performance is guaranteed, optimized circuit feedforward parameters are adopted for greatly and effectively reducing the complexity and the power dissipation of frequency dividing circuits.

Description

technical field [0001] The invention relates to the application field of fractional frequency division frequency synthesizers, in particular to a Sigma-Delta modulator and an operation method for the Sigma-Delta modulator. Background technique [0002] Frequency synthesis refers to the technology that can use one or more frequency sources to generate different frequency signals, and phase-locked loop is the most widely used frequency synthesis technology. figure 1 is the structural block diagram of the phase-locked loop, when the circuit is locked, the output frequency f of the phase-locked loop out with reference frequency f ref The relationship is: f out =N×f ref (N is an integer). Since the frequency divider can only carry out integer frequency division, the realization of fractional frequency division needs to add additional circuits. The main function of the SIGMA-DELTA modulator in the fractional PLL is to provide the frequency divider with an integer sequence con...

AI Technical Summary

Problems solved by technology

If there is no approximate conversion of the feed-forward coefficients of the system, a complex floating-point multiplier needs to be added in the circuit implementation

The traditional method is to use a floating-point number adder, although the calculation accuracy can be improved, but the chip area and power consumption are also greatly increased, and some structures will also be introduced into analog circuits.

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