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LNA - mixer driver
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.. image:: ../img/colorCode.svg
    :alt: color coded resistors

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

The signal source is isolated from the ground. It has a differential impedance of 300 Ω and a common-mode impedance of 0.5pF. The frequency range of interest ranges from 1 MHz to 250 MHz.

The load consists of a balanced mixer. It can be represented with two resistors of approximataly 50 Ω, connected to a common-mode power supply of 0.9 V. It should be driven with a differential current with a peak value of 500µA. Common-mode DC current through the load up to 10 mA is allowed.

The low-noise amplifier should have the following properties:

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