Departamento de Eletrónica, Telecomunicaçōes e Informática, Instituto de Telecomunicaçōes, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
The unfamiliar negative group delay (NGD) circuit is the less familiar function for most of RF and microwave design engineers. Among the existing types, the bandpass (BP) NGD type circuits are the most convenient for the wireless communication microwave technology. Therefore, it is particularly important to explore different microwave circuit topologies operating as BP-NGD function. An innovative design of BP-NGD topology constituted by defected ground structure (DGS) with complementary split ring resonator (CSRR) is developed in the present paper. The DGS-based BP-NGD structure design method is introduced in function of the CSRR geometrical elements followed by S-parameter parametric analyses. As proof-of concept (POC), the design method of the proposed BP-NGD passive fully distributed circuit is described. The effectiveness of the BP-NGD structure and the test feasibility are investigated by implementing two different prototypes represented by single- and double-wing DGS passive circuits. It is observed that significant BP-NGD function performances were validated by well-correlated simulations and measurements showing -1.9 ns NGD value around the center frequency, 2.46 GHz over 31 MHz NGD bandwidth. In addition, the tested BP-NGD prototypes present insertion loss better than 4 dB and reflection loss better than 16.7 dB. Because of its potential integration, the investigated BP-NGD circuit is potentially useful for the communication system performance improvement for example via delay effect reduction in the RF and microwave devices.
