Impedance bandwidth enhancement of low noise amplifier using photonic bandgap structures

A Compact Microstrip Resonant Cell (CMRC) structure has significant effect on the input impedance bandwidth of LNA. In this paper, we studied the effect of different CMRC structures on the performance of LNA. Different CMRC structures, ranging from λ_g/48 to λ_g/96 were implemented. Initially a simple LNA was designed in frequency band of 1.5 ~ 2.5GHz. The input impedance bandwidth was around 300 MHz when S₁₁ is ≤ -10dB. Now CMRC structure of λ_g/48 was implemented on simple LNA. The measured results show an improvement in the input impedance bandwidth up to 1.1GHz at the cost of some drop in gain, which may be attributed to feedback phenomenon. By reducing the size of CMRC structure to λ_g/96 i.e. Half CMRC (HCMRC), simulated results shows that 23% input impedance bandwidth can be further enhanced. In comparison, we also studied the Noise Figure (NF).