Compact transmission-type negative group delay circuit with low attenuation

• Published in: Electronics letters Vol. 53; no. 7; pp. 476 - 478
• Main Authors: Liu, Gang, Xu, Jinping
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 30.03.2017
• Subjects: Attenuation; bandwidth 35 MHz; cascaded two‐stage NGDC scheme; Circuit design; Circuits; compact transmission‐type negative group delay circuit design; delay circuits; distributed elements; Electronics; frequency 1.79 GHz; Group delay; loose‐coupling microstrip resonator; lossy coupled‐line resonator; low signal attenuation; lumped resistor; microstrip resonators; Microwave technology; MS resonator; open radial patch; Reflectance; reflection coefficients; Resistors; Resonators; Rogers RO4350B substrate; size 20 mil; two‐stage NGDC layout; UHF resonators; delay circuits; low signal attenuation; two-stage NGDC layout; Rogers RO4350B substrate; reflection coefficients; compact transmission-type negative group delay circuit design; size 20 mil; lossy coupled-line resonator; UHF resonators; frequency 1.79 GHz; loose-coupling microstrip resonator; distributed elements; open radial patch; bandwidth 35 MHz; microstrip resonators; lumped resistor; MS resonator; cascaded two-stage NGDC scheme
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2017.0328

A novel circuit is presented for the design of transmission-type negative group delay circuit (NGDC) with low signal attenuation. By loading a lumped resistor at a specific point on the loose-coupling microstrip (MS) resonator, a lossy coupled-line resonator is proposed, the size of which is effectively reduced by employing an open radial patch. A cascaded two-stage NGDC scheme is presented to realise an enhanced negative group delay (NGD) value and better reflection coefficients. The layout of the two-stage NGDC is designed in an anti-symmetrical back-to-back manner. To validate the performance of the proposed circuit scheme, a prototype of the two-stage NGDC has been designed, the working bandwidth of which is 35 MHz with a centre frequency of 1.79 GHz. This circuit is fabricated on Rogers RO4350B substrate with a thickness of 20 mil. A measured maximum NGD of −7.7 ns and a corresponding signal attenuation of as low as 8.6 dB have been obtained. Reflection coefficients are better than −20 dB. This NGDC occupies a compact size of 0.3λg × 0.18λg, which is much smaller compared to the previously reported NGDCs with distributed elements.