Abstract:

A C-Band broadband monolithic low noise amplifier is designed based on 0.15 μm GaAs PHEMT process.The circuit is formed by cascading three stages of amplifiers.To solve the problem of complex power supply,each of the stage uses a self-biased resistance to achieve a single power supply.It not only ensures PHEMT to work at an optimum operation point with low noise and high gain,but integrates all components (including the bias circuit) in a monolithic GaAs substrate also.A parallel negative feedback structure is used in the third stage of the circuit to reduce gain of the low-frequency band and raise gain of the high-frequency band,which improves the gain flatness of the amplifier.Results from simulation based on AWR Microwave Office show that the designed LNA has a noise figure(NF) below 1.4 dB,a power gain of 23 dB,a gain flatness of less than ±0.5 dB and input and output VSWR of less than 2.0 over the frequency range of 4～8 GHz.

Key words: self-bias;LNA;PHEMT;MMIC;C-band