Objective: to design a 900 MHz Low-Noise Amplifier (LNA) using a MMIC fabricated on a new ultra low noise GaAs ePHEMT process. To demonstrate a new noise performance bench mark (F = 0.3 dB at IRL ≤ - 15 dB) for the plastic-packaged device class.
Material: The LNA consists of a Microwave Monolithic Integrated Circuit (MMIC) and 9 passive components mounted on a 21.5x18 mm2 Rogers RO4350 micro-strip PCB. The MMIC, which comprises a common-source amplifier and temperature-tracking active bias, is fabricated on a new GaAs ePHEMT process optimized for noise. As loss in the input matching network is proportional to the source-to-input impedance transformation ratio, the transistor area was scaled and its operating current adjusted in order to reduce S11 to almost zero. The chip is packaged in an 8-pin Quad Flat Non-lead (QFN) measuring 2.0 x 2.0 x 0.75 mm.
Method: Scattering and noise parameters data of the MMIC, extracted on a commercial source-pull measurement system, were used to simulate the LNA. Based on the simulated circuit values, prototypes were built and measured. The measured results were used for model validation and for comparing with prior art.
Results: At nominal bias (5V, 50mA), the measured performances at 900 MHz are: G = 18 dB, F = 0.3, IRL/ORL < - 15 dB, P1dB = 22.3 dBm, OIP3 = 37.2 dBm and Linearity Figure of Merit (LFOM) = 15 dB. From HF to 20 GHz, the measured k exceeded 1; i.e. unconditional stability.
Conclusion: This plastic packaged MMIC enables low noise performance comparable to that of ceramic devices. Its linearity performance is also best-in-class.
- low noise amplifier,
Available at: http://works.bepress.com/chin-leong_lim/19/