Design Of Ka-band Ferrite Phase Shifter Deriving Circuit Based On CPLD

Phase shifter is the device which is able to adjust the phase of the electromagneticwaves. It is applied in the field of guidance, navigation, telemetry, electronic warfare,radar, microwave equipment and measurement systems, medical equipment and othermilitary and civil engineering systems. Above the S-band frequency, the ferrite phaseshifter is very advantageous in many ways such as power capacity, insertion loss,reliability and durability. It occupys a dominant position in the passive array. Ka-bandferrite phase shifter driven in the way of flux control is very easy to realize, and itsvolume is very small. It presents very low insertion loss and high accuracy differentialphase shift.In this paper, a controlling and driving circuit of4-bit Ka-band phase shifter basedon the CPLD devices was designed. The author elaborated the design ideas, anddesigned every module of the driving circuit. Firstly, the phase shifting booster moduleof the circuit was designed and realized, the output waveform reveals that it switchs thedifferential phase shift within5μs. Secondly, the pulse duration modulating module wasdesigned. It was able to output different set pulses. The duration of those pulses arevariable from60ns~2μs. The output waveform was measured and revealed that thismodule functioned properly. Lastly, the whole circuit was tested by working with sixferrite phase shifters made by our group. So far the maximum differential phase shiftmeasured is284.4°. The decoder for every phase shifter was designed to realize4-bitdigital phase shifting control. The RMS error of every phase shifter was calculated.Reasons for failure function was analyzed in detail, and some methods to improve thefunction of the circuit was proposed.