Predistortion circuit

Abstract

The invention relates to a predistortion circuit which can carry out linearization on any simulation transmission and device, belonging to the electrical technology field. The predistortion circuit comprises two parallel sub circuits. A power divider distributes a signal to the two sub circuits, each sub circuit is driven by one or more Schottky diodes, and two routes of signals are combined by a power combiner. The diodes of the two sub circuit are arranged in a reverse direction state, and both the two sub circuits can generate components of a first order, a second order, a third order and other higher-order. With the power combiner, all even-order components are offset, and only odd-order components like the first order, the third order, and a fifth order are remained, wherein third order inter-modulation distortion has a largest influence on signal transmission. The predistortion circuit is characterized in that: third order non linear distortion can be compressed, and predistortion adjustability is realized; according to a third order non-linear size generated by a non-linear transmission system, through adjusting offset voltage or current of the diodes of the two sub circuits, a third order non-linear component outputted by the predistortion circuit is changed, and compression maximization is realized.

Description

Technical field: [0001] The invention relates to a predistortion circuit capable of linearizing any analog transmission and device, and belongs to the field of electronic technology. In particular, it relates to a predistortion circuit capable of compressing third-order nonlinear distortion. Background technique: [0002] As we all know, subcarrier modulation (SCM) is widely used in satellite communication, wireless communication, radar and other systems. In other words, a wireless signal is composed of a main carrier and a sub-carrier, the main carrier (sine wave) carries the sub-carrier, and the sub-carrier carries a digital signal, which is analog transmission. After demodulation at the user end, the transmitted digital signal can be obtained. Unfortunately, when subcarrier modulation is applied, the nonlinearity of any device on the transmission line will cause nonlinear distortion, especially third-order intermodulation distortion. Due to non-linear distortion, for a...

AI Technical Summary

Problems solved by technology

[0005] Although analog predistortion technology has been proposed or applied in analog transmission, the existing predistorter has some defects and uses a large number of frequency-dependent devices, such as: phase shifters and amplifiers

This increases circuit complexity and cost, while introducing uncontrollable nonlinear distortion, making wideband predistortion difficult

Another disadvantage is that these devices require that the degree of distortion generated by each channel needs to be well matched. At the same time, the phase of the distortion needs to be inverse to the nonlinear distortion generated by the analog transmission, and the amplitude needs to be related.

Existing linearizing predistorters are difficult to tune, and in some cases the circuit requires complex tuning

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