Questions tagged [low-noise-amplifier]
The low-noise-amplifier tag has no usage guidance.
90
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Noise Figure in LTSpice
I'm simulating an LNA from a paper. It's using HBT BiCMOS technology an one of the things the paper shows is the simulation of NF in range of 3GHz to 10GHz. I'm trying to replicate the simulation with ...
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0
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Is an output noise in the micro range any good?
I have designed the below circuit, as mentioned in the previous post the input is a 50mV RMS @ 50Hz signal, the bandwidth is 1kHz, and the output amplifies this by 20V/V.
I have seen people do a ...
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1
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1
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85
views
How do you use an RC filter on an LNA output to reduce unwanted noise?
We designed two low noise amplifiers, one at 144 MHz and another at 440 MHz using this LNA; each design is tuned for the particular band. We noticed amplification at 440 MHz is clean and crisp, but ...
- 1,712
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113
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Low Noise - High DC Accuracy Voltage Reference Buffer ? Composite Amplifier?
I want to built a low noise voltage reference buffer to drive an ADC and additional analog circuits.
Main requirements:
"Ultra"-Low Noise
Best DC accuracy possible (mainly interested in ...
- 53
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1
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97
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What kind of relay is used for high-power RF front-end applications?
My son and I are designing an RF frontend at 146MHz with a 300W amplifier on the TX side an an LNA on the RX side to be placed near an antenna feedpoint. The frontend will be inline to an existing ...
- 1,712
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210
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When should you use a gate driver, and how do you choose one?
I'm building an amp using the NXP MRF300AN 300W LDMOS RF power amplifier device and was originally planning to use a DAC to drive the gate bias until @Hearth mentioned that I should use a gate driver. ...
- 1,712
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1
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60
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Does an LNA with a dedicated Vbias pin affect impedance matching?
I am optimizing an impedance match for an LNA in my target frequency range using a Touchstone s2p that Qorvo provides for the QPL9547 (datasheet).
The Vbias pin is separate from the RF-in pin. I'm ...
- 1,712
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120
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Can an LNA noise figure be normalized to dBm to estimate the minimum detectable signal?
If a device claims a noise figure of 0.3 dB NF such as the Qorvo QPL9547, can you calculate the dBm value of a signal that is at the noise floor (ie, a barely detectable signal)?
Otherwise stated: I ...
- 1,712
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7
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Transimpedance amplifier for very low currents
I am currently working on a project, which requires me to measure the very low currents (approximately in the range of 100 pA to 10 uA) from an electrochemical sensor.
The sensor is kind of a new ...
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242
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Digitally tunable gain, low-noise instrumentation amplifier
I want to make a digitally-tunable gain (~1 to 1000x), low-noise instrumentation amplifier. There are integrated ones (e.g. AD8557) but the input noise is too high. My current plan is to use an ultra-...
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1k
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How does an Instrumentation Amplifier reduce DC offset?
While researching different current measurement methods, I came across a particularly interesting circuit which has a very high input impedance and apparently reduces the effects of the input offset ...
- 633
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137
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I'm looking for an SMD diode in a (small) haystack, hearing aid repair [closed]
It works, but it buzzes through the earpiece if you turn up the volume much, I'd like to do some signal tracing, but first I'd like a schematic. I found one using 3 NPN transistors that might be close,...
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1k
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Noise figure to voltage noise spectral density hand calculation
The RF LNA of interest is the PGA-105+ from mini-circuits. From only the gain and noise figure I calculated the voltage noise spectral density that would be present at the amplifier input.
If anyone ...
- 83
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233
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How could I build an amplifier circuit that can take an input voltage of 0-0.7V and amplify to 0-32V, 1 ampere, that works for 100 MHz?
A little background first. I am trying to build a pretty dumb project where I try to take a VGA input and display it in a manner similar to a Nipkow disk.
The high frequency RGB signals need to be ...
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254
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Low noise electret microphone amplifier with automatic gain control
I am looking for a simple solution to design a low noise electret microphone preamplifier with automatic gain control (AGC.) Generally, I need to pick up the sound from a far distance, digitalize it ...
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Some LDO's specify noise in nV/Hz, others specify it in μV(rms). How do they equate?
The "low noise" LDO TI TPS7A20 specifies output noise as 7μV(rms) at 100kHz, whereas the Diodes AP2210 specifies output noise as 260nV/√Hz.
This SE answer compares the two mathematically as:
...
- 1,712
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63
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What are the qualities that you look for in a 2nd stage LNA?
We are building a multi-stage LNA for a TR module we are building in the 144MHz and 440MHz range.
The 1st stage LNA has to be the most sensitive---but what is important to consider when choosing a 2nd ...
- 1,712
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77
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How would you filter the DC input suitable for use to bias/power an LNA?
We are building a transmit/receive module for the 144MHz and 440MHz bands. As I understand, a good LNA can provide poor performance if the environment or the bias voltage is too noisy.
What are the ...
- 1,712
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2
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CNY70 and LM358 amplifier circuit not behaving as expected
I have reproduced a circuit proposed by Nicholas Burnett in 2013:
An improved noninvasive method for measuring heartbeat of intertidal animals please see Fig. 2
which looks as follows:
The circuit ...
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3
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276
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I need a pre-amplifier for my sound card with high gain without noise [closed]
I'm trying to make a pre-amplifier for my PC microphone with high gain and low noise.
I tried a few circuits but they had a lot of noise and low gain.
How can I make a preamplifier with high gain and ...
- 19
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63
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Additional gain with in-amp for nanovolt-scale pre-amp
Currently I'm designing a pre-amp for detecting nanovolt-scale(~100nV, <1kHz) signal for experiment. I need a final gain to be around ~100000. Since the magnitude of the signal is extremely small, ...
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185
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Photodetector and low noise amplifier acting as low pass filter
I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual....
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Building a “if” statement circuit where i can control different light diodes
I want to design a circuit to react in different ways depending if a microphone picks up one frequency and in different way if it picks up the some other frequency.
I want different lights to shine ...
0
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3
answers
153
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Audio amplifier components
I want to understand the purpose of capacitors and variable resistor in the following audio amplifier circuit. Here is its datasheet.
C118 at amplifier output pin.
C424 between amplifier input and ...
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1
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75
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How do you choose components for a gps antenna
I have to solder an active gps antenna on a pcb. But I don’t know how to choose components.
In my case antenna will be used outdoor on a pet collar.
First of all there are a lot of different ceramic ...
2
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3
answers
4k
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How to build a low noise MIC preamp
I want to be able to talk on the microphone of my Headset A and send that signal out to the earphones of my Headset B. Something similar to what I show you on the image below.
For that purpose, I ...
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3
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Do parallel LNAs at 90-degrees to eachother reduce the noise floor more than side-by-side?
Wiring amplifiers in parallel in a summing configuration improves the signal to noise ratio because amplifier noise in each LNA is uncorrulated. However, external noise sources will still be a factor ...
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306
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How does wiring two LNAs in parallel affect charactaristic impedance?
It appears that wiring amplifiers in parallel improves the signal to noise ratio. I thought I would experiment with two SAV-541+ LNAs in parallel and see how they perform:
How does wiring an LNA in ...
- 1,712
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3
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159
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Mic amplifier noise
I build a mic amplifier for a standard hands free (Apple 4-pole jack). However, even without anything plugged into the jack there's audible noise at the output (MIC_IN in diagram). It sounds like ...
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228
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Understanding Noise Figure of LNA (HP 461A amplifier)
I have recently got a HP 461A linear amplifier (from the 60's) which works from 1Khz to 150Mhz.
I have checked that:
it's input gives a SWR <1.1 across all spectrum (i.e., the input impedance is ...
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2
answers
537
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Ultra low noise charge sensitive preamplifier
I developing charge sensitive preamplifier for radiation detector. This is a very sensitive device, the smallest amount of noise can completely ruin the signal.
The schematic and the PCB you can see ...
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0
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131
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12-15V to 9V power supply required to power audio equipment
I have a 12-0-12 transformer with output after filtering 15-16V.
It's for audio equipment uses. I want to power a guitar pedal with 9V. I tried L7809 but it's making a whistling noise, so I tried ...
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2
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330
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Understanding the circuit diagrams for white noise generators
I'm a huge neophyte when it comes to electronics, and I'm trying to work out how to create a white noise generator for a project. I've been looking at some to base my examples off of. One of which is ...
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272
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How to measure Johnson Noise precisely experimentally?
I want measure Johnson Noise across a resistor having certain over the certain range of frequency or bandwidth practically. I am starting from scratch, how can I build circuitry and instrumentation so ...
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4
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In a Class-C power amplifier, what does the resistor in the base do?
Look at the picture, which shows a Class C power amplifier (source). What is the role of the resistance in the base of the transistor, and what happens if it's removed?
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Can a Unilateral Amplifier be Unstable?
When designing microwave amplifiers, stability is an important factor to consider. Stability is usually measured with the K factor. In a unilateral network, S_12 = 0, and this makes the K factor ...
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67
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Selection of Frequency in Switching Regulator
The AD ADP5070 for feeding a low noise amplifier and a 24 bit ADC, can be regulated at two pin selectable frequencies: 1.2MHz or 2.4MHz, accepting an external oscillator in the range 1 MHz to 2.6MHz.
...
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3
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129
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Unkown DIP IC (OP277PA)
I stumbled upon the most uncommon thing. An 8-PIN DIP IC with part number (OP277PA.)
However, the datasheet is nowhere to be found and I've done my research.
Is it possible that it is an OPA277P, or ...
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0
answers
281
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Choice of passive components for AD549/AD630 low-noise circuit?
I'm trying to reproduce an "ultra" low-noise amplifier circuit which calls for several precision amplifiers/modulators (AD549/LF356/AD630). The input source is a Hamamatsu S1223 photodiode capturing a ...
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3
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How to reduce an audio system noise in a way which is similar to a human touching one of the system's components?
I have a somewhat weird question (hopefully not too weird).
I work with an audio system. It includes a wave generator, a (33500B series Keysight) wave generator, an amplifier (2003 op-amp based ...
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2
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1
answer
517
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What's the catch with these JFETs?
I'm designing a low-noise, high-bandwidth (100 MHz) pre-amp using JFETs. The choice for JFETs was because it needs to operate with large source impedances (>10 kΩ).
I spent a while looking for a ...
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Origin of increased noise in BF862/OP27 charge amplifier
For the amplification of piezoelectric sensor signals I am currently building a charge amplifier with a low noise JFET frontend utilizing an NXP BF862. The amplifier design is based on application ...
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152
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Matching Networks on Narrowband Multistage Low Noise Amplifier (LNA)
How does the inter-stage matching network of a narrowband LNA compare to that of a wideband LNA for the same multistage design? I've read somewhere that narrowband LNA does not necessarily require a ...
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776
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Effects of impedance mismatch on RF signals from antenna
I'm building an antenna array that operates at high frequencies (around 2 GHz).
I want to use a SDR dongle that has a 75 ohm input impedance as receiver, I've also bought the coax cable, a 4 way ...
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2
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455
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Why voltage source has been connected via inductor at the output of LNA?
I have been reviewing the schematics of LoRaWAN Gateway designed by Microchip (Page 48). The output of the LNA has been connected to voltage source via inductor.
...
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2
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582
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Low-pass Filter with zero drift amplifier
Can an auto-zero or chopper amplifier be used in a low-pass filter to remove a high frequency carrier? I am trying to design an active low-pass filter with a 1kHz cutoff and very low DC drift, offset, ...
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4
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475
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How to amplify RF signal to high enough level for a CMOS downconverting mixer?
I've been reading original academic papers on mixers and now a RF textbook and I have been unable to understand a very basic thing, which is how do I get a RF signal, say -65 dBm, at a high enough ...
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How may noise voltage and noise figure be compared?
For instance, comparing the
MIC920
and the
BGA2818,
it's expected that since the latter is intended for application as an RF LNA and the former is general-purpose, the BGA2818 would out-perform the ...
- 3,102
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809
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Antenna preamplifier design for ELF Schumann resonances receiver
I'm interested in listening to extremely low frequency band below 100Hz, where the famous Schumann resonances reside. I will use a large T shape antenna together with a very low noise, very high ...
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467
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Use Raspberry Pi to power a low noise inverting amplifier with negative voltage input
I am looking to use a Raspberry Pi to power and read the current from a current-to-voltage converter. I am currently using two batteries to power the operational amplifier, as shown in the schematic ...
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