A 0.08–3GHz high gain UWB LNA with improved flatness

An ultra-wide band (UWB) low noise amplifier (LNA) of bandwidth 0.08-3GHz, gain more than 28dB, flatness fluctuating in ± 1dB and noise-figure less than 2.3dB is designed and tested. This LNA utilizes the characteristic of reactance value changing with frequency, especially, adopts capacitance negative-feedback in source electrode to compensate the decrease of high frequency gain. Comparing with traditional inductance negative feedback between drain electrode and gate electrode, this adding capacitance feedback can improve gain-flatness obviously. Furthermore, a transmission line of λ/4 is used to achieve broadband match of input and output port, as a result, the voltage standing-wave ratio (VSWR) of input and output port don´t exceed 2. Simulated and measured results are in good agreement.