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Amplifier Circuits: Low Noise Circuits
Last Updated on:
Friday, April 25, 2008 04:12 PM |
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Amplifier -- Main Page
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| Circuits Designed by Dave Johnson, P.E. : |
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| Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students &
inventors: |
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Adaptive Noise
Cancellation: (electronic circuit added 10/06) |
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Composite Amplifier Improves Noise : 08/04/94 EDN-Design Ideas / (Electronic Schematic / circuit added 4/02) Amplifying low-signal
levels for signal processing often stretches a single op amp's abilities. A composite design can improve the input noise for detecting
extremely small signals and can enhance output-drive ability. Both the op amp's noise terms and the thermal noise of the components limit the
minimum noise in an op-amp-based design. Furthermore, amplifier noise figures are not at their minimum for low-impedance sources such as 50
Ohm. Using a transformer is a common technique to achieve matched input impedance for maximum power transfer. Fig 1 shows one example, which
follows the transformer with a composite amplifier to achieve a lower input noise figure.... |
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Low Noise
Amplifier for Phase Noise Measurements: features less input noise than a 50 ohmresistor. (Electronic circuit added 7/03) |
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Low Noise Balanced
Microphone Preamp: very low noise, close to the theoretical minimum, high hum rejection and variable gain with a single rotary pot,
similar to that used in many professional grade mixing desks (Electronic circuit added 7/03) |
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Low Noise
Microphone PreAmplifier: (Electronic circuit added 7/03) |
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Low-noise ac
Amplifier has digital Control of gain and Bandwidth: 02/05/2004 EDN-Design Ideas In low-noise analog circuits, a
high-gain amplifier serves at the input to increase the SNR. The input signal level determines the input-stage gain; low-level signals require
the highest gain. It is also standard practice in low-noise analog-signal processing to make the circuit's bandwidth as narrow as possible to
pass only the useful input-signal spectrum. (Schematic / circuit added 10/05) |
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