KCC's Quizzes AQQ304 - A pure logic
1. Quote of the month: "I am not lazy, I'm just in energy-saving mode" - unknown
2. Quiz AQQ304 about finding a pure logic puzzle
Mike is looking at Anne, but Anne is looking at Paul.
Mike is married, but Paul is not.
Question:
Is a married
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September Monthly Blog Quiz! Read the blog, take the quiz, and you could win a gift card
Quiz: How Well Do You Know Adaptive Power Switching?
Is your I/O module overheating? The AD74416H's Adaptive Power Switching (APS) can cut heat dissipation by up to 40% — but how well do you really understand how it works?
Read the blog first: Cooling
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AD604
Production
The AD604 is an ultralow noise, very accurate, dual-channel, linear-in-dB variable gain amplifier (VGA) optimized for time-based variable gain control...
Datasheet
AD604 on Analog.com
I'm using the AD604 as a low-frequency amplifier from 2 kHz to 2 MHz. Figure 17 only shows input-referred noise from 100 kHz up. Is there characterisation data or a typical 1/f corner for the preamp below 100 kHz? I'd like to know whether the 0.8 nV/√Hz still holds below 10 kHz.
Also: Table 1 lists input bias current as "−27 mA" but Figure 34 shows 27 µA. So, I assume mA is a typo?
Hi LearningRF,
We don't have characterization of AD604 1/f noise corner below 100kHz. For your 2kHz application, please also consider the AC coupling capacitors discussed on page 16 of the datasheet. The 0.1uF capacitors and the 175 ohms DSX input resistance form a high pass filter with a corner frequency of approximately 9.1kHz. Larger coupling capacitors are needed to extend the low-frequency response.
Regarding the input bias current, you are correct. The -27mA specification is a typo. The correct unit is uA, consistent with Figure 34. Thank you for bringing this up, I will report this to the team for correction in future datasheet revision.
Best Regards,
Ian
Hi ianguieb ,
Thank you for the reply. I'll size the coupling capacitors for my corner frequency.
Understood that the AD604 isn't characterized below 100 kHz. Could you confirm whether you'd expect it to meet its datasheet specs at my frequency of operation?
If it isn't suitable, could you suggest an ADI VGA that is characterized at that frequencies with similar specs?
Best Regards,
Tushar
Hi ianguieb , just following up on this. Could you confirm if the AD604 will still meet specs at 2 kHz, or is there another VGA you'd recommend?
