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RF Electronics Chapter 6: Oscillators Page 199 2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0. Figure 6.45 shows the spectrum obtained from the oscillator. The oscillator has a clean output signal and an acceptable phase noise performance. The output frequency is 990 MHz, which is within 1% of the design value. The output power is +5 dBm. Dual Resonator Oscillator Figure 6.46. Circuit schematic for 1GHz dual resonator oscillator. It is desirable to design oscillators, which produce the least amount of phase noise for a given frequency and tuning range. The primary factors determining the phase noise of the oscillator are the Q of the resonant network, the noise figure of the amplifier and its output power. Leeson's [3] simplified model for phase noise shows the phase noise is inversely proportional to the square of the Q of the resonator. The higher the Q, the more rapid the resonator's change of phase with frequency at the resonance. Figure 6.47. Simplified Circuit Schematic for 1GHz Microstrip coupled dual resonator. By using two resonators that are coupled, a faster change of phase at the resonance can be obtained, thus reducing the phase noise. Figures 6.39 and 6.40 show a single resonator. Ld21=17.16 Ld22=20+Ld21 1 2 3 MTEEX ID=TL13 W1=3 mm W2=W50 mm W3=W50 mm MLIN ID=TL6 W=W50 mm L=Ld21 mm MLIN ID=TL5 W=W50 mm L=Ld22 mm MTAPER ID=MT2 W1=3 mm W2=1.2 mm L=6 mm Taper=Linear Method=Default MTAPER ID=MT1 W1=3 mm W2=1.2 mm L=5 mm Taper=Linear Method=Default CHIPCAP ID=C2 C=27 pF Q=390 FQ=500 MHz FR=2030 MHz ALPH=-1 CHIPCAP ID=C1 C=10 pF Q=390 FQ=500 MHz FR=2030 MHz ALPH=-1 MLIN ID=TL8 W=1.85 mm L=14.18 mm MLIN ID=TL7 W=3 mm L=2 mm MSUB Er=3.38 H=0.8128 mm T=0.035 mm Rho=0.7 Tand=0.0027 ErNom=3.38 Name=SUB1 MTAPER ID=MT3 W1=3 mm W2=W50 mm L=3 mm Taper=Linear Method=Default MLIN ID=TL9 W=3 mm L=2 mm MLIN ID=TL2 W=3 mm L=2 mm PORT P=3 Z=50 Ohm PORT P=2 Z=50 Ohm PORT P=1 Z=50 Ohm 1 2 SUBCKT ID=S2 NET="DualResonator" 1 2 SUBCKT ID=S1 NET="mar6sp" MLIN ID=TL12 W=W50 mm L=4 mm MCURVE ID=TL4 W=W50 mm ANG=90 Deg R=5 mm MCURVE ID=TL11 W=W50 mm ANG=90 Deg R=5 mm MLIN ID=TL3 W=W50 mm L=7.02 mm MCURVE ID=TL1 W=W50 mm ANG=90 Deg R=5 mm 1 2 3 4 OSCTEST ID=O1 WL=5 Sc1=5 Lr=Lt2-2*Lc2 Lc2=6.12 Lt2=38.8 Rc=204 MLIN ID=TL11 W=W50 mm L=1 mm W1 W2 1 2 3 4 M2CLIN ID=TL2 W1=WL mm W2=WL mm S=Sc1 mm L=Lc2 mm Acc=1 MLSC ID=TL1 W=WL mm L=1 mm MLEF ID=TL9 W=WL mm L=0.1 mm MLSC ID=TL4 W=WL mm L=1 mm MSUB Er=3.38 H=0.8128 mm T=0.035 mm Rho=0.7 Tand=0.0027 ErNom=3.38 Name=SUB1 1 2 3 MTEE ID=TL6 W1=WL mm W2=WL mm W3=W50 mm MLEF ID=TL5 W=WL mm L=0.1 mm MLIN ID=TL7 W=W50 mm L=3 mm PORT P=1 Z=50 Ohm W1 W2 1 2 3 4 M2CLIN ID=TL13 W1=WL mm W2=WL mm S=Sc1 mm L=Lc2 mm Acc=1 W1 W2 1 2 3 4 M2CLIN ID=TL12 W1=WL mm W2=WL mm S=Sc1 mm L=Lr mm Acc=1 MLIN ID=TL8 W=WL mm L=W50 mm RES ID=R1 R=Rc Ohm CHIPCAP ID=C1 C=0 pF Q=390 FQ=500 MHz FR=2030 MHz ALPH=-1 MLIN ID=TL10 W=WL mm L=W50 mm 1 2 3 MTEE ID=TL3 W1=WL mm W2=WL mm W3=W50 mm PORT P=2 Z=50 Ohm 1 2 3 MTEE ID=TL14 W1=W50 mm W2=W50 mm W3=3 mm RF Electronics: Design and Simulation 199 www.cadence.com/go/awr

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