Hello, I'm looking for a schematic of the amplifier with band from DC to 100 MHz and impedance 1Mohm for 14bit ADC converter. I googled only simple solutions based on eg AD8138 with trafos and imput impedance only 50 ohm
Any sugestion?
Peter
Amplifier, adc driver
Jan 07, 2015
7 Replies
Den onsdag den 7. januar 2015 23.46.27 UTC+1 skrev snipped-for-privacy@gmail.com:
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-Lasse
1 pF has an impedance of 1.6K at 100 MHz!
Need more details about the application to say much more.
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
So what. 1Meg || 10 pF is not unusual for 100 or 200 MHz scopes.
regards, Gerhard
But that's a resistance of 1M in parallel with a capacitance of 10p. The _impedance_ ain't 1M at 100MHz!
The OP is neither specific enough (does it literally have to be an impedance |Zin| = 1M, and if so, at what frequency(ies)?) nor very practical (14 bits at 100MHz, no really?).
Tim
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com
Need more details about the application to say much more.
typical scope probe-> IN -> res divider+varcaps (1/10 - 1/100?) -> fet opamp(s)? -> some amp with single input and dif output -> VGA -> ADC
Are you designing an oscilloscope? SE hiZ in, then a differential ADC? Do you need switchable gain ahead of the ADC?
John Larkin Highland Technology, Inc
picosecond timing laser drivers and controllers
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
I need only one channel similar to what is in oscilloscope. VGA can be controlled by the SPI or analog.
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