Design Of Sine Wave Signal Conditioning Module For Oscilloscope Calibrator

It is a direction for oscilloscope gradually that owning the function of testing higher frequency signal and provide a more precise measurement results,with the development of modern electronic technology.As a tool to debug,test and calibrate the oscilloscope,oscilloscope calibrator,Obviously,have to provide test signal,which is higher precision,higher frequency and higher quality than the detection capability of oscilloscope.The design of this topic is a sine wave signal conditioning channel that can deal with the signal frequency up to 3.2 GHz,which will meet the needs to calibrate the most of oscilloscope currently.The analog conditioning channel of sine wave can determine many parameters of the oscilloscope calibrator output signal,such as signal amplitude,flatness,harmonic noise,etc.The most difficult of the subject designs is how to complete the sine wave signal conditioning funtiong and ensure the purity of output signal.The main contents of this research include:1.Analyzing the design criterion of the analog conditioning module,and then designing the piecewise control scheme about the overall program.The conditioning channel will be divided into two part based on the frequency.The signal of low frequency band will be synthesized by conditioning module,and the signal of high frequency band can be provided by external module.How to design the conditioning unit of high frequency is the key of the whole project design.2.Designing the signal generator and conditioning unit of low frequency band.Studying several signal synthesis technology and using direct frequency synthesis technology to generate low-frequency sine wave signal.Let the signal to be adjusted in the conditioning unit and to meet technical requirements finally.3.Designing the signal conditioning unit of high frequency band.Aiming at the amplitude accuracy and the controllable minimum conditioning amplitude of the output signal,the radio frequency signal continuous and adjustable voltage-controlled attenuation circuit is designed.And to achieve the control of amplitude range of output signal,using passive attenuation chip and power amplifier chip to design conditioning circuit.4.Radio frequency realys are used in order to achieve the input signal to select the amplification/attenuation circuit or pass-through function,analyzing the impact of signal transmission frequency characteristics and the interference between signals after using radio frequency relays,and then make up improvement measures.5.The loss of radio frequency signal power during transmission is a common problem,but some measures can reduce the loss.Researching and analyzing the signal integrity design in high-speed PCB design,optimizing the layout and routing in high-frequency signal conditioning circuit.