Research And Implementation Of Handheld Spectrum Analyzer’s Local Oscillator

The rapid development of technology has brought great convenience to people’s lives and back to greater challenge to the research work. The development of wireless communication technology promotes more field work tasks,so it’s imminent to research the portable devices used in field work. Handheld Spectrum Analyzer is a portable field instrument widely used in field measure tasks. Under the background of the handheld spectrum analyzer project, based on the premise of high bad environment adaptability, this thesis studied and achieved the local oscillator of the handheld spectrum analyzer under the principles of the low power consumption and small size designing.Firstly, this thesis introduced the basic theory of the superheterodyne spectrum analyzer and its soul, and then comparatived the advantages and disadvantages of high-frequency and low frequency tuning program. Combined with the development of the local oscillator technology,this thesis ultimately determined the high-frequency tuning program of the handheld spectrum analyzer. By analyzing the overall project targets of the handheld spectrum analyzer,this thesis draw a detailed index of its local oscillator module. Secondly, by combining with the 3GHz RF spectrum analyzer LO program, this thesis designed the phase-locked loop frequency synthesis scheme with low power consumption. this thesis combined the PLL frequency synthesizer technology with the low-power design techniques. and designed the power control scheme of voltage-controlled oscillator and the low-power solutions of the fractional frequency technology. In order to ensure only one oscillator work,this paper designed the programmed switch to control its power supply,and ultimately limited the switch off time to less than 60 ns by ADS simulation optimization. The low power consumption of the fractional technology mainly refered the double modulus divider,which consumption is only 0.02 W. Finally, by circuit simulation, PCB drawing board and hardware debugging, this thesis had realized the local oscillator of the handheld spectrum analyzer. This article innovatively designed the local oscillator by only using voltage-controlled oscillator, and the use of low-power technology successfully reduced the power consumption of the local oscillator circuit.This thesis finalized the overall design goals of the handheld spectrometer’s local oscillator module. The low-power technology successfully controlled the overall power consumption of the oscillator circuit within 7W. The output signal’s phase noise of the circuit reduced-90dBc/Hz@10kHz, 4.88 GHz, and frequency resolution had reached 1Hz.