Specific harmonic cancellation multi-level radio frequency pulse width modulation method and modulator

Abstract

The invention discloses a specific harmonic cancellation multi-level radio frequency pulse width modulation method in which K odd number of specific harmonic waves are selected, and M-level RF-PWM signals are processed to be equivalent to N 3-level RF-PWM signals with pulse width separately controlled by corresponding comparison thresholds and stacked in a weighted manner, wherein K, M and N are all integers more than 0, N is more than K, and M is equal to 2N+1; N comparison thresholds and corresponding weighting coefficients are controlled in real time according to a normalized envelope signal SA, so that the K specific harmonic wave components of the N 3-level RF-PWM signals has stacked in a weighted manner are mutually counteracted, a base wave component is in direct proportion to the SA, and thus the K specific harmonic waves and integer multiples of odd harmonic waves of the M-level RF-PWM signals are eliminated. Based on the method, the invention also provides a specific harmoniccancellation multi-level radio frequency pulse width modulator. Compared with the prior art, the modulation method and the modulator have the beneficial effects that on the basis that the basic modulation performance is equivalent to the RF-PWM of the same level in the prior art, the suppression requirement on the filter is effectively reduced, the cost and size of the filter are reduced, and thus the comprehensive performance of the wide frequency band DTX is improved.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a specific harmonic elimination multilevel radio frequency pulse width modulation method and modulator. Background technique [0002] The transmitter is one of the important components of the wireless communication system. Its role is to up-convert the modulated baseband signal to radio frequency (RF), and amplify the radio frequency signal to a power level sufficient for antenna transmission. It is the main factor that determines the output signal quality and work efficiency of the wireless communication system. Smaller size, lower power consumption, higher communication rate, digitization and reconfigurability are the development direction of the transmitter. In recent years, the high-efficiency, wide-band digital transmitter (DTx) technology combined with direct digital radio frequency modulation (DDRFM), switched mode power amplifier (SMPA) and tuned filter has develope...

AI Technical Summary

Problems solved by technology

[0026] In the prior art, for DTx applications, it is necessary to implement RF-PWM in the digital domain. Due to the discrete characteristics of time and amplitude of digital signals, whether it is 3-level or M-level RF-PWM, its modulation performance and sampling The minimum time resolution (that is, the minimum discrete time interval) is directly related to the time, and is limited by the physical realization of RF-PWM. Its limited minimum time resolution will bring nonlinear distortions such as spurs, intermodulation and noise floor. In order to improve The performance of the existing technology RF-PWM, high-performance digital delay line (DDL) technology based on semiconductor technology is widely used [P.A.J.Nuyts, et al., "A fully digitaldelay line based GHz range multimode transmitter front-end in 65- nm CMOS,” IEEE J. Solid-State Circuits, vol.47, no.7, pp.1681-1692, 2012; P.A.J. Nuyts, et al. “A fully digital PWM-based 1 to 3GHz multistandard transmitter in 40-nmCMOS , "in 2013 IEEE Radio Frequency Integrated Circuits Symposium, pp.419-422, 2013], the DDL technology based on 40nm CMOS process, its minimum time resolution can reach 4ps, thus significantly improving the overall performance of the existing RF-PWM performance, but it also puts forward higher requirements for semiconductor process and design complexity, and will bring higher implementation costs

[0027] From the introduction and analysis of the above background technology, it can be seen that although the prior art MLRF-PWM reduces the quantization noise by increasing the quantization level, it can effectively improve the coding efficiency of RF-PWM and reduce harmonics to a certain extent Distortion, but the problem of a large number of high-order harmonic components in RF-PWM has not been fundamentally resolved, and a tuned filter with a high quality factor is still required to suppress harmonics

However, the tuned filter with high quality factor has problems such as complex design, insertion loss and large size, which will restrict the broadband performance of DTx

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