Numerical control attenuation circuit and adjusting method thereof

Abstract

The invention relates to a numerical control attenuation circuit and an adjusting method thereof. A main attenuation circuit of the numerical control attenuation circuit comprises a first main attenuator and a second main attenuator which are connected in series, a first attenuation fine tuning circuit and a second attenuation fine tuning circuit, the first attenuation fine tuning circuit and thesecond attenuation fine tuning circuit comprise a plurality of triodes and resistors, bases of the triodes are connected with a decoding control circuit through the resistors, and collectors are connected with analog signal output ends of the first main attenuator or the second main attenuator through the fine tuning resistors. An attenuation value suitable for a fine tuning resistor is selected to finely tune the circuit, and the precision of attenuation stepping is improved. According to the adjusting method of the numerical control attenuation circuit, the output end of the main attenuationcircuit is connected with a vector network analyzer, the attenuation fine tuning circuit is disconnected firstly, the attenuation amount is detected at the moment, the attenuation error of the main attenuation circuit is obtained, and the fine tuning resistance value of the attenuation fine tuning circuit required for supplementing the error is calculated. According to the invention, the steppingattenuation precision of the attenuator in which the two chips are connected in series is improved and reaches 0.2 dB, the composite design of the double chips and the attenuation fine tuning circuitnetwork is easy to realize and adjust.

Description

technical field [0001] The invention relates to an analog signal amplitude adjustment technology, in particular to a numerically controlled attenuation circuit and an adjustment method thereof. Background technique [0002] The original signals in nature are all analog signals, such as sound, image, brightness, radio waves, etc. Most of these analog signals need to change their amplitude when radio users use them. In the field of amplitude control of low and intermediate frequency analog signals, common applications include shortwave radio signals, radar intermediate frequency signals and other low and intermediate frequency analog signals. These signals are required to be adjusted in amplitude during application to meet the signal interface requirements of subsequent circuits. [0003] The amplitude adjustment of the analog signal is mainly divided into two ways: mechanical adjustment and electronic adjustment. The mechanical adjustment method is to act on the variable re...

AI Technical Summary

Problems solved by technology

Existing digitally controlled attenuator chips cannot meet the attenuation accuracy index while meeting a large attenuation range

When the general numerical control attenuator attenuates the input signal with a large value, due to the influence of various factors such as circuit noise, the signal-to-noise ratio of the output small signal after attenuation is low, and the attenuation error increases, which cannot meet the requirements of current technology development for attenuation accuracy.

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