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Noise-Source-with-3xGALI.php    7316 Bytes    08-07-2024 13:49:20

An easy to build Noise Source

With just 3 x GALI or 3 x GVA or anything in a SOT-89 case.

The photomodel comes with a Voltage regulator. Supply was 9 V, 123 mA. The final Version also has an Attenuator at the output. For Fine Adjustement of the Level and Improvement of the Matching. BOM is approx. 123 CHF.

✈ Motivation

Motivated by the Version with 2 x GVA-81+ we wanted to continue towards the 'Ghetto Blaster'. Still, the Amplitude response is not too shabby.

Some theroretical max. ENR values (without attenuator) mayst be :


In order to calculate the ENR value from the Noise Floor Measurement, we used this website. The above ENR was measured with three identical Gain Blocks. The 50Ω Resistor produces a Noise of -113.1 dBm in a 300 kHz Bandwidth at 290 K.

Depending on your Selection of Amplifiers, the Bias Network as well as the Voltage Supply mayst need to be altered. Bias Calculator for MCL's Monolithics Amplifiers.

✈ Performance

With 3 x GALI-19+ and PAT-3 the ENR value is : 38.18 dB @ 1.0 GHz
And yes, we know that graphs end, where data becomes unflattering. Please believe me, I only have a FSP-3 from Rhode & Schwarz (3 GHz) High Precision Spectrum Analyzer 🙁

✈ Increasing S22 - #0001

ON ... better 20 dB
OFF ... better 20 dB

As some Tester will switch the Noise Source ON and OFF, the Output matching must be very good, in both cases. This can be accomplished by increasing the attenuator at the output to higher values. Using an attenuator of 15 dB, we can increase the matching by 30 dB. Yes, the ENR will drop by 15 dB. In terms of ENR, we measured the following values :

✈ Downloads

✈ Share your thoughts

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t1 = 6586 d

t2 = 191 ms

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