Application Description

A low-noise RF amplifier converts the voltage of 300Ω balanced floating source into a current for a mixer.

Target specification

• Input impedance: 300Ω ± 5%
• Frequency range (−3dB): 1 · · · 250MHz
• Differential output impedance: > 10kΩ
• Noise figure @300Ω source impedance: < 2.5dB over the frequency range of interest.
• Gain from input voltage to load current 40mS±10%
• IM3 distortion at 100MHz (5mVp at 200MHz and 5mVp at 500MHz) < −66dB
• Maximum Peak differential output current < 500μA
• Supply current @1.8V supply voltage < 20mA

Environmental conditions

The audio amplifier should operate from 0 to 70 degrees Celsius.

Design tasks

Design the LNA according to the specifications above. You can use CMOS18 devices. The circuit should operate from at 1.8V±5%.