Questions tagged [low-noise-amplifier]

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3answers
58 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
38 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
106 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 ...
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1answer
59 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 ...
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2answers
91 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
73 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 ...
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2answers
221 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
72 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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0answers
36 views

What is the Intuition behind the Stability Factor (K) in Microwave Amplifiers?

In microwave amplifier design, there is a Rollett's stability factor (included below), which determines if the amplifier can be unstable. If K > 1, the amplifier is always stable, and if not, it could ...
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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
33 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
52 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. ...
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3answers
111 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
78 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 ...
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3answers
193 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
316 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
621 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
88 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
338 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
185 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
301 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
287 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
455 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 ...
2
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2answers
362 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 ...
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1answer
256 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
110 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 ...
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1answer
87 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 ...
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0answers
240 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 ...
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1answer
166 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
137 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
436 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 ...
1
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3answers
192 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
43 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
215 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) ...
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1answer
149 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
297 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 ...
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2answers
211 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
408 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 (< $...
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3answers
116 views

Optimizing dynamic range for acquisition of noisy signal

Is there a good rule of thumb for setting the gain of a noisy signal before digitization? Say I have a 16-bit ADC with a ±1V range; to what level should I amplify the noise floor of my signal relative ...
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2answers
1k views

How to design wide band amplifiers?

I've been designing microwave power amplifiers and LNAs for school, I design in microstrip and my matching networks usually consist of stub/line sections or similar arrangements, I have also designed ...
4
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1answer
709 views

What type of transistor generally has the lowest flicker noise?

How do BJT vs JFET vs HBT compare in terms of \$1/f\$ noise amplitude and corner freqency? I know these transistor types are very different, used for different frequencies and powers, and each have ...
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2answers
99 views

Noise performance at cryogenic temperature

I want to know what kind of improvemend electronic circuits get at cryogenic temperatures.I looked at online noise calculator and it shows that if I go from room temperature to 1 kelvin the noise ...
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1answer
90 views

RF (2.4GHz) LNA board with multiple amplifier stages: Should I use multiple voltage regulators?

I'm working on a LNA board to work in the 2.4GHz band. I'm using broadcom/avago MGA-635P8 amplifiers. Since I need more gain than a single stage can give me, I'm using 3 stages in cascade (although ...
1
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1answer
819 views

Pmos or Nmos? Which has the biggest contribution to flicker noise?

I would like to ask if this sentence below is correct.I had find it, when I was reading a paper. "PMOS transistors have lower flicker noise than similarly-sized nMOS transistors in most CMOS ...
4
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2answers
96 views

Need help understanding why noise temperatures are added, but real temperatures aren't

Wikipedia says: In a wireless communications receiver, the equivalent input noise temperature \$T_{eq}\$ would equal the sum of two noise temperatures: $$T_{eq} \ = \ T_{ant} \ + \ T_{sys}$$ I ...
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4answers
2k views

Impedance matching vs. voltage gain

So I have an ultrasound system operating in the 1-10MHz range: Pulser -> Tuning circuit -> Transducer -> Tuning circuit -> Voltage amplifier The goal is, I'm trying to optimize the tuning circuits ...
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1answer
1k views

How to measure Noise Figure of LNA

I know how to calculate Noise figure of an amplifier on the paper but how can measure Noise figure of a LNA in real world? Our lab doesn't have a fancy Noise figure meter but I can readily access to ...
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2answers
460 views

I am looking for recommendations how to lower the noise in this preamplifier circuit

I have a circuit using MMBT3904T-7-F parts, operating at 100uA collector current, which is rather noisy. This is a preamp for the 475kHz ham band. I need to stick with bipolar NPN. How can I lower ...
12
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7answers
1k views

Amplifying a nV signal across a small resistance

I am interested in the feasibility of amplifying/measuring a nV level (or otherwise assumed very small) signal across a small resistance. The SNR of this signal isn't so bad in itself because of the ...
3
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3answers
1k views

Why do we care about matching the input impedance of receiving RF amps?

Lets say we have a receiving antenna that intercepts a certain amount of power \$P_r\$ = \$SA_r\$, where \$S\$ is the power flow density of the incoming EM wave, and \$A_r\$ the effective area of the ...