A specific harmonic elimination multi-level radio frequency pulse width modulation method and modulator

Abstract

A multi-level radio frequency pulse width modulation method for specific harmonic elimination, selects K odd specific harmonics, and converts M-level RF-PWM signals into N pulse widths controlled by corresponding comparison thresholds. RF-PWM signal weighted superposition, K, M, N are all integers greater than zero and N>K, M=2N+1, according to the normalized envelope signal S A Real-time control of N comparison thresholds and corresponding weighting coefficients, so that K specific harmonic components of N 3-level RF-PWM signals after weighted superimposition cancel each other out, and its fundamental component and S A proportional to the K specific harmonics of the M-level RF-PWM signal and its integer multiple odd harmonics. Based on the above method, the present invention also provides a multi-level radio frequency pulse width modulator for specific harmonic elimination. Compared with the prior art, the beneficial effects of the present invention are: on the basis that the basic modulation performance is equivalent to that of the same level RF-PWM of the prior art, the suppression requirement for the filter is effectively reduced, the cost and volume of the filter are reduced, thereby improving the broadband DT X comprehensive performance.

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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