Questions tagged [low-noise-amplifier]

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2answers
97 views

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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1answer
60 views

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 ...
4
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2answers
268 views

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: ...
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0answers
51 views

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 ...
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32 views

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 ...
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2answers
92 views

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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3answers
109 views

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 ...
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0answers
24 views

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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0answers
30 views

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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0answers
44 views

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 ...
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3answers
105 views

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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1answer
56 views

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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3answers
839 views

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 ...
1
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3answers
66 views

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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1answer
81 views

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 ...
5
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3answers
120 views

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 ...
5
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1answer
104 views

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 ...
4
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2answers
156 views

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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0answers
88 views

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 ...
1
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2answers
250 views

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 ...
2
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1answer
74 views

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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4answers
2k views

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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1answer
43 views

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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1answer
57 views

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. ...
2
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3answers
114 views

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 ...
2
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0answers
130 views

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 ...
7
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3answers
200 views

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 ...
2
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1answer
369 views

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 ...
2
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1answer
818 views

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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1answer
102 views

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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1answer
473 views

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 ...
3
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2answers
284 views

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. ...
2
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2answers
377 views

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, ...
1
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4answers
329 views

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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2answers
806 views

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 ...
5
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2answers
507 views

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 ...
1
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1answer
336 views

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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2answers
122 views

Multiband LNA Design [closed]

I am familiar with circuit design - Basic Op-Amp Design, concepts like stablity, Phase margin and I am a beginner in Microwave Engineering. I am familiar with some basic ideas and little familiar with ...
0
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1answer
129 views

Using an RF adapter to improve LTE signal in the house

In my apartment, the GSM signal is very scarce, if not absent at all, except for a few spots, where there's a decent LTE signal and I can browse internet reliably. In order to improve the reception ...
0
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0answers
275 views

LNA using Common Emitter with feedback collector

I am trying to design an LNA with input impedance of 50 Ohms, I am considering the topology illustrated below. I have found an online calculator that computes this however when I try to work out the ...
1
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1answer
196 views

Inconsistent Gain with Instrumentation Amplifier

I'm trying to prototype an instrumentation amplifier with OPA2111 as the first stage and INA105 as the second stage on a breadboard. The circuit diagram is similar to this: Power rails are connected ...
5
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1answer
167 views

Microphone Amplification

I am working on a project using a microphone/microcontroller combination to detect if a clap has occurred. Thus far, I am using the Electret Microphone Amplifier - MAX4466 with Adjustable Gain from ...
1
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3answers
574 views

Monitor tiny variation in voltage

I should apologize if my question is trivial since I did not find a similar question, I decided to specifically ask mine. I have a microscopic membrane in my lab, this piece which we call it NMS has ...
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3answers
251 views

Low noise amplifier DC gain

This circuit provides 30dB gain to a 100kHz signal with a 10k input impedance. Is capacitor C2 necessary to suppress DC gain or is it redundant with the AC coupled input? I would also like to make ...
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0answers
45 views

Need help understanding a fairly vague solution to example problem (the topic is noise in CMOS circuits)

So I have the solution to the following example problem I am working on: Now the issue is that I am trying to understand the solution I was given: The thing is this solution is simply quite vague. ...
5
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1answer
251 views

Electrochemical Measurements Using Lock-In amplifier

I'm trying to measure small electrochemical signals using a trans-impedance amplifier fed into a lock-in amplifier. I have an electrochemical cell that poses a very high impedance (100s of MegaOhms) ...
1
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1answer
155 views

Ιnput referred noise of an amplifier

I have a problem with a low noise amplifier because I can't find in ADS(Advance design system) software how to integrating under the are of a measured curve in a specific frequency range.Can someone ...
2
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1answer
315 views

MMIC RF Amplifier BGA2817 vs. Discrete Transistor/s Amplifier?

I've been working on learning transistor 101s, for a 900MHz transmitter. I'm to the point, I can work the basic algebra, and intuitively understand changing the passive components in the transistor ...
0
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2answers
238 views

Is Gain Block can be used a Power Amplifier

I have chosen 2 datasheets of MMIC Power Amplifier: HMC311ST89 MMIC AMPLIFIER – DC-6GHZ -16db Gain HMC637ALP5E – DC-6GHZ – 13db Gain My intention is to use the 1st one as Power Amplifier. I was ...
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3answers
430 views

Amplify coil antenna signal

Suppose I have a coil antenna that receives an ideal 100kHz ~200uVpp signal which I would like to measure. Can this signal be amplified to 2Vpp (10,000x gain) with 1% error for moderate cost (< $...