In this paper, a novel X-band push-push oscillator employing dual-feedback sub-oscillators and a half-wavelength microstrip line resonator is presented. The dual-feedback sub-oscillator consists of a series feedback commonly used in conventional oscillators due to its good phase noise performance and a parallel feedback circuit which improves both the output power and stability. The resonator and power combiner form a single circuit allowing compact size. Measured results show that an excellent output power of +13.3 dBm was obtained at the second harmonic frequency of 9.81 GHz. Moreover, superior phase noise of -105.0 dBc/Hz and -123.5 dBc/Hz were achieved at 100-kHz and 1-MHz offset frequencies, respectively. The suppression of undesired harmonic signals, namely fundamental and third harmonic signals, are 27.9 dB and 55.7 dB, respectively. With a simple design structure and compact size the proposed push-push oscillator achieved very good performance.
2. Lee, Y. T., J. Lee, and S. Nam, "A new phase noise reduction method of oscillator by loaded Q improvement using dual feedback topology," IEEE Microw. Wireless Compon. Lett., Vol. 15, No. 1, 39-41, Jan. 2005.
3. Pavio, A. M. and M. A. Smith, "A 20-40 GHz push-push dielectric resonator oscillator," IEEE Trans. Microw. Theory Tech., Vol. 33, No. 12, 1346-1349, Dec. 1985.
4. Xiao, H., T. Tanaka, and M. Aikawa, "Push-push oscillator with simplified circuit structure," Electronics Lett., Vol. 38, No. 24, 1545-1547, Nov. 2002.
5. Xiao, H., T. Tanaka, and M. Aikawa, "A low phase noise Ku-band push-push oscillator using slot-line resonator," 2004 IEEE MTT-S Int’l. Microw. Symp. (IMS2004) Dig., 1333-1336, Jun. 2004.
6. Choi, J. and C. Seo, "Low phase noise push-push VCO using microstrip square open loop multiple split ring resonator and rat race coupler," Proc. 2010 Asia-Pacific Microw. Conf. (APMC2010), 394-397, Dec. 2010.
7. Du, Y. C., Z. X Tang, B. Zhang, and P. Su, "K-band harmonic dielectric resonator oscillator using parallel feedback structure," Progress In Electromagnetics Research Letters, Vol. 34, 83-90, 2012.
8. Su, P., Z. X. Tang, and B. Zhang, "Push-push dielectric resonator oscillator using substrate integrated waveguide power combiner," Progress In Electromagnetics Research Letters, Vol. 30, 105-113, 2012.
9. Chang, H. C., "Stability analysis of self-injection-locked oscillators," IEEE Trans. Microw. Theory Tech., Vol. 51, No. 9, 1989-1993, Sep. 2003.
10. Wang, T. P., Z.-M. Tsai, K.-J. Sun, and H. Wang, "Phase-noise reduction of X-band push-push oscillator with second-harmonic self-injection techniques," IEEE Trans. Microw. Theory Tech., Vol. 55, No. 1, 66-77, Jan. 2007.
11. Wu, C. T. M., T. Ithoh, A. K. Poddar, and U. L. Rohde, "Active complementary coupled resonator for low phase noise x-band oscillator," 2014 European Freq. & Time Forum (EFTF2014), 356-359, Jun. 2014.
12. He, F. F. and K. Wu, "A low phase-noise VCO using an electronically tunable substrate integrated waveguide resonator," IEEE Trans. Microw. Theory Tech., Vol. 58, No. 10, 3452-3458, Dec. 2010.
13. Florian, C., S. D’Angelo, D. Resca, and F. Scappaviva, "A chip set of low phase noise MMIC VCOs at C, X, and Ku band in InGaP-GaAs HBT technology for satellite telecommunications," 2017 IEEE MTT-S Int’l. Microw. Symp. (IMS2017) Dig., 1148-1151, Jun. 2017.
14. Zhang, H., W. Kang, and W. Wu, "Configuration for realizing a push-push parallel-feedback oscillator through a differential bandpass filter," IEEE Access, Vol. 6, 28514-28519, May 2018.