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  • 2.225 ghz phase locked mmic coaxial resonator oscillator for space applications

    Paper ID



    • Alak Banik
    • Rati Singh
    • Sarathi Mandal







    {\bf Purpose:} Large number of Local Oscillators is used for receivers, up converters on-board Satellite transponder. PLL Technique combined with MMIC based coaxial resonator oscillator is designed and developed to space qualify 2.225 GHz local oscillator which provides smaller mass, volume, size and higher reliability in comparison with other technique such as TCXO followed by multiply-filter-amplify approach. {\bf Methodology: } • The paper describes the design and realization of the microwave MMIC coaxial resonator phase-locked oscillator (CR-PLO) for use as a local oscillator in space qualified C-band receiver. The PLO unit combines the long term stability and excellent close in phase noise of TCXO with superior phase noise of MMIC CRO at higher offset frequencies. • A GaAs negative resistance MMIC based coaxial resonator oscillator is phase locked to a temperature Compensated Crystal Oscillator (TCXO). The MMIC with on chip power divider and buffer amplifiers at two output port is designed using ED02AH GaAs technology. The design of MMIC negative resistance stage is described with design yield of 87\% and on wafer measurement is in good agreement with simulated results. The chip is hermetically packaged.This packaged MMIC with off-chip coaxial resonator \& varactor diode is used to build CRO which is locked to TCXO by an analog Phase Locked Loop using Sampling Phase Detector. • The paper extends the design of Sampling Phase Detector and other RF circuits in the feedback path like ring filter, isolation amplifier, directional coupler for monitoring the LO signal along with PLL design considering optimum loop Bandwidth for good phase noise and other PLL dynamics. {\bf Results:} • The individual designed and developed sub-circuits of the PLO are compared with simulated and measured results. • The integrated PLO is designed \& developed at 2.225GHz with output power of 5 dBm, –80 dBc spurious and harmonic better than –45 dBc. The PLO consumes 140 mA at 15 Volts, weight 450 grams and approximate size is 135 mm x 80 x 38 mm. • This PLO approach made it possible to integrate LO and RF tray into a single compact C-Band receiver package. {\bf Conclusion:} A Space qualified MMIC based Phase locked CRO is designed, implemented and qualified for space use. The non-integration of the on-chip resonator provided the flexibility of the negative resistance MMIC for other wider applications to build CRO within 2.0 -3.0 GHz with proper phase matching of the resonator circuit with device input impedance to satisfy oscillation condition. Apart from RF performances, the PLL performance is also verified with hold-in range and phase noise. The each subsystem of the PLO is elaborated with design and test results. The unit has under gone various stages of qualification tests as per ISRO’s space qualification plans. {\it end}