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Questions tagged [mixer]

A mixer or frequency mixer is a nonlinear electrical circuit that creates new frequencies from two signals applied to it.

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Why do direct conversion receivers amplify only after mixing?

The vast majority of the simple direct conversion receivers I've seen amplify only after mixing. The RF is filtered before mixing, but not amplified at all. For example (from Solid State Design for ...
SRobertJames's user avatar
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BJT Gilbert cell with emitter-degeneration

I am trying to design a Gilbert cell mixer. I am stuck on one requirement. Background: The RF differential voltage swing should above 900mVpp (currently RF=991.2mVpp.) This swing must remain the same....
Tom's user avatar
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switchable summing audio mixer volume troubles

Consider this audio mixer. There are 3 sources that may play any kind of audio (the sine generators are just illustrative). You can switch any of them to either of 2 outputs using the SPDT switches. I ...
one_three_three_seven's user avatar
1 vote
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Second Opinion on Superheterodyne Receiver Design

I've design a superheterodyne receiver for frequencies between 88-108MHz. Below shows the final schematic and I wanted to get a second opinion on it. Specifically, I wanted to know if the general ...
TheButterMineCutter's user avatar
2 votes
1 answer
153 views

Incorrect Output of RF Mixer

I've designed a RF mixer (Gilbert Cell) which takes a RF frequency between 88-108MHz and a LO of 77.3-97.3MHz, I want to take the difference between the two so the IF is 10.7MHz. Currently, the output ...
TheButterMineCutter's user avatar
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Displacement current in Gilbert cell mixer

I'm trying to design a double balanced Gilbert cell mixer as part of a course. I'm having trouble with eliminating the peaking of the switching current. I know that this happens due to the parasitic ...
Ddh Hhd's user avatar
2 votes
0 answers
88 views

Advice on active line-level audio mixer using a single supply rail

A few years ago a asked a question about an active audio (line level) mixer I wanted to make. I got some advice about how to run it off a single supply to make things easier and I was hoping to come ...
Jaska's user avatar
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-2 votes
4 answers
102 views

RF signal chain gain

In conventional electrical signal chain design, we now exactly what is the amplitude of signal in any node, from source to load. In radio frequency circuits which contains antenna. We don't know the ...
mohammadsdtmnd's user avatar
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Cascaded RF amplifiers - "wiggliness" and flatness

I'm designing an application that requires distribution of an LO to a large number of mixers from a single source. The frequency range is 15-18G (3G BW) and the input power level is -5 to +5 dBm (10dB ...
cplusruss's user avatar
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1 answer
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Resistor choice for passively mixing line level and speaker level

There are a lot of great resources here for people who want to mix together multiple outputs of the same or similar load impedance. However, in my case, I want to mix a mono, amplified, ground-...
Kenn Sebesta's user avatar
4 votes
2 answers
317 views

Schematic review for an ultrasonic heterodyne mixer

I'm building a heterodyne ultrasonic bat detector with a mems microphine (Knowles SPU0410LR5H-QB) and the SA612 mixer. I have built it on a breadboard and it works. It has some hum and noise but I ...
Gos's user avatar
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LM386 Amplifier Mix Dual Audio Signals

I am trying to build an audio amplifier which will get input from an electret microphone and music signals from mobile using aux cable. I found a schematic diagram in the Circuit Digest website which ...
Kailash Kumaravel's user avatar
6 votes
1 answer
343 views

Radar received RF signal phase-shifted by 90 to obtain I/Q signals

I am trying to get idea how marine radar works before start any repairing process. And this part confused me, most articles that i saw explain that in mixing stage we obtain I/Q signals using LO ...
Tremax's user avatar
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3 votes
3 answers
166 views

Passively mixing two (or perhaps more) speaker-level audio signals, without additional downstream amplification

I have several voice-radios with amplified mono outputs. The radios are designed to connect directly to a 4Ω speaker. I would like to connect two (or more) of them to the same speaker. The radio ...
Kenn Sebesta's user avatar
0 votes
2 answers
393 views

Audio Mixer Circuit with Individual Volume

I'm trying to make an audio mixer circuit based on the amplifier circuit published by Scott Campbell. I have no knowledge of opamps so I'm taking it mostly as-is but the input signal I am going to ...
SukkoPera's user avatar
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3 answers
319 views

Bats ultrasounds detector with LM324

I have some questions about this small project, a device to detect bat ultrasounds and reproduce in a speaker. It's based in a post of the Element14 community, Episode 578. I have adapted it and I'm ...
Gos's user avatar
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Do we require matching circuit and stability in Gilbert cell active mixer design? If yes then what is the procedure?

I'm trying to simulate a Gilbert cell active mixer using a PHEMT transistor model in ADS. I've referred some articles of Gilbert cell active mixer design but I haven't found any matching circuit or ...
Aparna B's user avatar
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Audio mixer, one output to multiple inputs

I'm trying to create a device that will take one stereo input and send it to 4 or more audio Bluetooth transmitters. This way, I can connect my prjoector to it and everyone watching can listen in on ...
user8833400's user avatar
3 votes
4 answers
1k views

Volume gets lower when left and right audio channels are combined

I noticed that the volume of a speaker gets slightly lower when combining the left and right channels versus having ONLY one of the 2 channels connected to the speaker. I know that combining the left ...
Stelios Liakopoulos's user avatar
2 votes
2 answers
177 views

Why would a mixer output a signal when only LO is present and RF input is terminated?

I have a mixer with a liner frequency sweep going into the LO port, and a terminator on the RF port. I've noticed that this produces a significant signal at the output. It resembles what we would get ...
R McHenry's user avatar
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3 answers
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What should be connected to pins 3 and 4 of this 1/4 inch mono jack?

What should be connected to pins 3 and 4 of this 1/4 inch mono jack?
zupp's user avatar
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67 views

How to set the output impedance of this circuit?

Assuming no biasing, would setting the Re to 300 Ω be the proper method of impedance matching? simulate this circuit – Schematic created using CircuitLab I figure that at some point, a ...
Yousif Alniemi's user avatar
0 votes
1 answer
110 views

RF mixer output

I have three questions with respect to an RF mixer. Let us consider this component - ADE-35MH+ from mini-circuits. The component has three pins - LO, RF, and IF. What is the output on IF? Is it LO + ...
enemra's user avatar
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288 views

Mixers and LO Harmonics

Say we have an RF signal with components at \$F_{LO}+\Delta\$ and \$3F_{LO}+\Delta\$ and we want to down-convert so that \$F_{LO}+\Delta\$ becomes \$\Delta\$. We will mix this RF signal with our local ...
Fraser Price's user avatar
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1 answer
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Master pitch control for oscillators

I’m doing a project of four oscillators where each one allows switching between a sawtooth or square waveform. The diagram that I attach is the corresponding one for a single oscillator, each one has ...
Zlmanuel87's user avatar
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1 answer
69 views

Can I use the local oscillator and intermediate frequency pins as inputs on an HMC220B RF mixer?

My goal is to take an FM signal centered at 5.8 GHz and up-convert it to 6.5 GHz, amplify and transmit the signal, then down convert the received signal from 6.5 GHz to 5.8 GHz on the receiver side. I ...
Spencer Brennessel's user avatar
1 vote
2 answers
521 views

In an audio mixer, when is it necessary to match the input impedance of other devices?

I found an audio mixer design that introduces a 47k resistor on each input. Credit: Graham Lambert According to the designer: We want the input impedance presented to each input to be constant and ...
Nick Bolton's user avatar
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1 answer
288 views

Bias tee in Vector Network Analyzer

Can I use a bias tee in the back of a VNA (E5080B) as a port 1 and 2, or do I need a mixer for it? I want to measure the network parameters of a device that requires bias.
Ferrofluid's user avatar
1 vote
1 answer
197 views

Instrument level to line level and mixing

I would like to convert an instrument level (guitar) to a line level in order to feed the isd1820 sampler chip. What are my option in order of doing so? In addition - I would like to mix the four ...
lon_ly's user avatar
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4 votes
2 answers
257 views

Can I compress the dynamic range of ns pulses to better fit ADC range using log amp or mixer?

I have an experiment in which the signal I want to measure is a 1 ns pulse that occurs somewhere around 0-100 ns after a trigger. I want to digitize the pulses to extract the time they occurred and ...
argentum2f's user avatar
1 vote
3 answers
435 views

Frequency upconversion from 1 to 100 MHz for FM transmitter

I'm trying to build an FM transmitter like pifm but using the ESP32. I can generate an FM signal at the DAC output of the ESP32 with a carrier frequency of 1 MHz and a deviation of 25 kHz, but in ...
Hamdon's user avatar
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3 votes
1 answer
353 views

Dangers of local oscillator signal being stronger than radio frequency signal in mixer

Recently as an interview question for an RF engineer job, I was asked the following question. What are the dangers of having a local oscillator power level much higher than that of the RF power level ...
CMH12's user avatar
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4 votes
3 answers
559 views

Self-biasing diode in mixer applications

I am working to understand this application's mixer design note. An image of the mixer is shown below. It uses two transistors and a hybrid ring coupler (rat-race coupler). What I am having trouble ...
CMH12's user avatar
  • 181
-1 votes
1 answer
160 views

Why does this passive mixer have such a high noise figure?

Here is the circuit: And here is the noise figure as a function of frequency: It is a big value. Why? You can see the passive mixer here:
Scipio's user avatar
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71 views

Push to talk mic over music

I have an amplified mic and I want to mix it with an mp3 player output. I tried something like this without a relay (just a button with 2 pairs of contacts), but I hear a pop when I press the button (...
Cătălina Sîrbu's user avatar
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0 answers
72 views

Sizing a mixer circuit

Here's the question: Here's my attempt: The table where i got the transistors values: And here's the circuit i implemented in LTSpice: The simulation results was a failure.... The output voltage ...
Scipio's user avatar
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1 vote
2 answers
74 views

What does \$\small-X(f+f_{LO})\$ mean in this passive downconversion mixer?

In the images below I circled one expression in red. There's supposed to be a frequency shift, but what does -X(f+fLO)/j·π mean here, and how is Y1(f) equal to the output spectra in figure 2.22(b)? ...
Scipio's user avatar
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0 votes
2 answers
95 views

Generating DC signal using a phase detector

I can generate a DC signal using a splitter and a phase detector. I do this by splitting a signal to two and then mixing them in a phase detector (I can also use a mixer as well for this purpose). By ...
saeid 's user avatar
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4 votes
2 answers
346 views

Audio mixer comments/concerns

I'm trying to design an audio mixer for my friend, and he only needs three stereo channels with volume for each channel as well as a master volume. Additionally, he'd like as high an audio quality as ...
Lucas Henry's user avatar
2 votes
2 answers
446 views

Determining LO drive voltage for 13dBm mini-circuits mixer

I am interested in using the following mixer by mini-circuits: RMS25-MH+. In the datasheet it is specified that the required LO drive power is 13dBm. As i understand it double balanced mixers use ...
Dylan Muller's user avatar
0 votes
1 answer
137 views

Mixer noise calculation

It is not clear for me how a mixer generates noise. Lets say that we take an up-converting mixer there is certain white noise level at LO input - \$N_{LO}\$ and a certain level of a white noise at RF ...
Pierre Polovodov's user avatar
7 votes
4 answers
2k views

What's the purpose of the band-pass filter in an RF transmitter?

What is the purpose of the marked band-pass filter?
LucasSokol's user avatar
0 votes
1 answer
381 views

Relation between signal mixer and filters

Mixer output shown as red wave: Can a band-pass filter be used to remove the low frequency shown as a blue sine wave and leave the rest high frequency just like the frequency shown as a green sine ...
LucasSokol's user avatar
1 vote
0 answers
93 views

Clarification on I/Q Mixer output

I'm working on RF Receiver, it is required to use I/Q Mixer for IF downconversion. Specification as follows below ...
Dinesh 's user avatar
0 votes
4 answers
192 views

FM transmitter won’t work. I need help with more gain, and current at the output

I am trying to make an FM transmitter circuit using cascaded transistors. My two input signals are from a microphone and from an 80 MHz crystal. I’ve calculated a gain of 22 from the first stage and ...
Sean772's user avatar
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0 votes
1 answer
81 views

Mixer design : IF is +/- DC volts, local oscillator is cosine 9.6 kHz

I am working on a mixer which will be used for 4QAM, QPSK. The local oscillator is 9.6 kHz and the IF would be + or - 1 volt DC in order to have the RF port output either cosine or -cosine. Which ...
user3425949's user avatar
3 votes
3 answers
1k views

Cost-efficient mixers and/or demodulators for low frequencies

I am working on a circuit project where I need an in-phase/quadrature mixer for acoustic signals in the range of 200 kHz. I have seen that there are a lot of ICs for radio frequencies that implement a ...
PeterO's user avatar
  • 195
0 votes
2 answers
283 views

Why does the IF of an RF mixer not go down to DC?

Consider this mixer: “SMA Triple Balance Mixer RF/LO Freq. 6-18 GHz IF Freq. 2-8 GHz” If my RF is 18 GHz and my LO is 17 GHz then the IF should be 1 GHz. But the product somehow has a minimum of 2 GHz....
student1's user avatar
  • 767
2 votes
1 answer
230 views

Help in smoothing signal output from a frequency mixer

I have a circuit with a TFM-3MH+frequency mixer. I need to output a low frequency signal of 10-100Hz. The signals that I'm sending to the input ports from a signal generator are: Sine wave of ...
Nikola Petrovic's user avatar
0 votes
2 answers
336 views

Where to add equalization in active audio mixer?

I want a 2-input summing amplifier where I can adjust the amount of signal from each source with a single potentiometer. I intend to hook up two microphones (Shure SM57 and Audio Technica ATR 1500, ...
Walden Marshall's user avatar

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