We have revived the super-regenerative techniques, invented by Armstrong in 1920s, by creatively using its dynamic processing in mm-wave and sub-mm-wave imaging applications. Super-regenerative circuits are based on quench-controlled oscillators to sense input signals at the crossing point when the overall transconductance transitions from positive to negative. Due to the periodical compensation to the oscillator, super-regenerative based receivers demonstrate ultra-high sensitivity due to high quality factor Q of the dynamically compensated resonant tanks. The receiver also eliminates the needs for power hungry amplifiers due to large output signals of super-regenerative circuits. Therefore, super-regenerative receivers (SRR) often result in a much more compact size, lower power consumption, and higher sensitivity than its heterodyne and direct conversion counterparts. We have demonstrates several SRR receivers for various systems and applications, including active CMOS imagers at 140 GHz and 183 GHz with the ultra-low power consumption of 2.4 mW/pixel, a 349 GHz active CMOS imager consuming 18.2 mW, a 3-D imager by using sub-carrier successive-approximation radar algorithm with 0.76 cm resolution in 2 µs integration time, and a 4×4 focal plane array imager consuming 13.4 mW/pixel. The revived super regenerative technique has led to more than 10× better energy efficiency and smaller chip area than SOAs. We have published 7 papers and filed 1 patent application in this domain.
- S. Ma, H. Yu, Q. J. Gu, and J. Ren, “A 7.52 dB NF, 128.75-132.25 GHz Super-Regenerative Receiver with 0.615 fW/Hz0.5 NEP by Coupled Oscillator Networks for Portable Imaging System in 65nm CMOS,” IEEE TMTT, September 2018
- Tang, Q. J. Gu, and M.-C. F. Chang, “CMOS Receivers for Active and Passive mm-Wave Imaging,” invited paper to IEEE Communication Magazine, vol. 49, no. 10, Oct. 2011
- Tang, Z. Xu, Q. J. Gu, Y.-C. Wu, and M.-C. F. Chang, “A 144 GHz 2.5mW Multi-Stage Regenerative Receiver for mm-Wave Imaging in 65nm CMOS,” IEEE Radio Frequency Integrated Circuits Symposium (RFIC) 2011
- Tang, G. Virbila, D. Murphy, F. Hsiao, Y.-H. Wang, Q. J. Gu, Z. Xu, Y.-C. Wu, M. Zhu, and F. Chang, “A 144GHz 0.76cm-Resolution Sub-Carrier SAR Phase Radar for 3D Imaging in 65nm CMOS,” 2012 IEEE International Solid-State Circuits Conference (ISSCC), February 2012
- Tang, G. Virbila, Y.-H. Wang, Q. J. Gu, Z. Xu, L. Du, N. Yan, Y.-H. Wu, Y.-C. Wu, M.-C. F. Chang, “A 200 GHz 16-pixel Focal Plane Array Imager using CMOS Super Regenerative Receivers with Quench Synchronization,” 2012 IEEE MTT-S International Microwave Symposium, June 2012
- Tang, Q. J. Gu, Z. Xu, G. Virbila and M.-C. F. Chang, “A 349 GHz 18.2mW/Pixel CMOS Inter-modulated Regenerative Receiver for Tri-Color mm-Wave Imaging,” 2012 IEEE MTT-S International Microwave Symposium, June 2012, Third Place – Best Student Paper