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Questions tagged [mixed-signal]

A circuit which contains both analog and digital signals.

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Can you help me understand this transient output of this universal biquad filter? My Bode plot proves that the filter is working perfectly [closed]

I am designing a universal biquad filter in LTSpice and ASLK Pro board with a square wave input: I have taken the Q factor as 1. I'm not convinced it is right. Is it as simple as the ratio of RQ/R6?...
Rohan C's user avatar
1 vote
1 answer
34 views

How do the switches and level translator work in the LMC7660 Switched Capacitor Voltage Converter [closed]

This is the block diagram of Texas Instruments LMC7660: Here 4 switches are used S1 to S4. The diagram shows source connection of only two transistors S1 and S2, and leaves out the S3 and S4 switch. ...
Newbie_Programmer's user avatar
2 votes
1 answer
54 views

Best practice for via stitching of multiple GND planes with analog and digital on different PCB sides

I'm quite well aware of standard practices of grounding in mixed signal application. I bascially always use just one large common ground and use wise component placement to keep current transients ...
jusaca's user avatar
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Code transition glitches in an ideal DAC

I have read in most books and articles that a code-to-code glitch is caused by imperfect timing in the switching of bits into a DAC. If that was true, then there should be no glitch when you use an ...
Borenstein Boar's user avatar
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1 answer
60 views

Ultrasound System Design: Navigating Transmission Line Challenges and Impedance Matching

Hello community! I'm currently working on the design of an ultrasound scanning system, and I'm seeking guidance, particularly in the realm of high frequency PCB design and transmission lines. My ...
Sepehr's user avatar
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70 views

Fully isolate digital and analog sections to reduce EMI when driving DC loads with PWM. I2C data corruption

I am working on a mixed-domain portable secret project based on the venerable ATMEGA2560 that will essentially control 3 DC heaters using MOSFETs, communicate with an external controller via UART and ...
Daniel Melendrez's user avatar
2 votes
0 answers
59 views

Ground isolation in multichannel mixed-signal systems

There are some similar questions to mine but I have a few more specifications on top of them. Therefore, I am not 100% sure whether to ask as an iteration or present my own question on a clean slate. ...
falsterbo's user avatar
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1 answer
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How to interpret the equivalent circuit of a true bipolar SAR ADC?

I am referring to ADS8548 (Datasheet). How do I interpret this equivalent circuit of the input of the ADC? CH_XX would be where the analog voltage is fed and AGND ...
Efanatic's user avatar
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0 answers
45 views

Smooth out signal from remote sensor

I have a remote (wired) device with a MOSFET and some analog sensor with some inherent noise I want to smooth out. I decided to go with a simple RC filter but upon inspection I realized that my signal ...
DARK_DUCK's user avatar
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4 votes
1 answer
254 views

How does this AGND to DGND connection work?

I'm working on an audio circuit, and part of the circuit looks like this: simulate this circuit – Schematic created using CircuitLab What is going on with this circuit? The ground has a lot of ...
brazed_blotch's user avatar
1 vote
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105 views

Comparators that can drive large capacitive loads

I quote from Allen and Holberg, 3e, Pg 468: If a comparator has a large capacitive load, the chances are that it is slew rate limited. Under these conditions, we will show several methods capable of ...
Suryadeep Mandal's user avatar
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1 answer
408 views

Split ground plane for electrical isolation between sections that source from the same supply?

I am currently in the process of designing a high-precision mixed signal PCB. I do have some experience designing simpler PCBs, and I have been doing my own research for this question. However I ...
BlueOyster's user avatar
1 vote
1 answer
124 views

How much of my mixed-signal PCB should I shield with a Faraday cage?

I'm designing a PCB with an AFE (Analog Front-End) for measuring/recording bipotentials and I'm trying to determine how much of the circuit I should shield with a Faraday cage. At the moment, I'm ...
Dionysus's user avatar
1 vote
0 answers
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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31 views

Where is the output resistance of M5 in the Output Resistance Expression

Attached is the gain expression of the circuit
debashish's user avatar
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29 views

Cascaded D-FF with Async Clocks Output Trouble

I am trying to latch the output of a D-FF_1 into D-FF_2. When I apply a rising edge to the clock input of D-FF_2, and the output state of D-FF_2 changes, the output of D-FF_1 freezes, and gets "...
Yet Another Michael's user avatar
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49 views

Connecting Split Power planes for mixed signal PCB

I'm working on a mixed signal board, and I currently have 3 power planes, 12V, 3.3V analog, and 3.3V digital. I have a single GND plane with good separation between the analog and digital components. ...
Mostafa Ibrahim's user avatar
1 vote
1 answer
143 views

Allowed amount of input wreal data type at verilog-ams

I'm a newbie at using Verilog-ams and also I want to write a module for flash ADC for a specific application. I need to confine my voltages reference so I wrote this Verilog-ams code for testing input ...
Marziye Hasanshahi's user avatar
1 vote
1 answer
177 views

Number of data points needed for INL DNL estimation

In this article where ADC of pico pi is characterized, I found a part that I have never encountered in my study of mixed signals design: I don't understand how we number of data points needed is ...
Kutsit's user avatar
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2 answers
735 views

Ground Pours or Thieving for Filling Unused Space on PCB Signal Layers

Often at the end of a PCB design there is unused space on the signal layers. It is important to fill this space because of: The electroplating process (valid only for TOP and BOTTOM) The even ...
Ivan Vlaykov's user avatar
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4 answers
191 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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1 vote
2 answers
47 views

Mixed signal PCB components placement

I'm designing a PCB that contains digital and analog parts. I'm thinking of placing the digital parts closest to the source and analog parts farther from the source and after the digital parts. The ...
MrBit's user avatar
  • 2,053
2 votes
1 answer
3k views

When does a PCB require a chassis ground connection?

Do all PCBs require a chassis ground connection point? I am designing a circuit board which will be used in many different types of assemblies. It is a small mixed-signal, low-voltage (24 VDC power, ...
rothloup's user avatar
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3 answers
887 views

Is there an implementation of mixed analog (SPICE) and digital (HDL) simulations?

I wonder how it could be possible to do mixed circuits simulations. In my imagination, there is a circuit netlist which contains analog and digital components. Since XSPICE (and I think ngspice) has ...
Paul M's user avatar
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1 vote
1 answer
415 views

Balun or fully differential amplifier (or both) as a differential ADC driver at MHz frequency?

AD9655 ADC The signal is AC coupled so I don't "need" the DC coupling availability of FDAs. I don't need another gain stage either, so the FDA would be in a 0dB gain configuration. My main ...
Max W's user avatar
  • 83
0 votes
5 answers
301 views

Do differential ADC's really reject 100% of common mode noise?

Say you have differential signals that are perfectly phase and amplitude balanced, but obviously 180 degrees out of phase V+= Asin(2pif*t)+ Vcommon_mode_noise V-= -Asin(2pif*t)+ Vcommon_mode_noise The ...
Max W's user avatar
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-1 votes
1 answer
1k views

What is your preferred circuit simulator for high-performance analog/mixed signal? [closed]

I'm starting a new job and I've been using NI multisim in school, but I am trying to decide if I should learn a new spice simulator. Not sure how to compare Multisim to something like LTspice which my ...
Max W's user avatar
  • 83
0 votes
1 answer
472 views

PWM to voltage for servo control

I have Chinese "no name" servo drives with following inputs for speed and torque mode: I have got a MESA 6I25 card and want to use LinuxCNC as a controller. I want to design a BOB (break ...
PSz's user avatar
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1 answer
129 views

Differential Pair Mode Conversion [closed]

What is the purpose of using these mode conversions? SCD Input: Differential Output: Common SDC Input: Common Output: Differential
Roy Roif's user avatar
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1 answer
101 views

How stable should this power supply be?

I am designing a system with a variety of sub-systems. The voltage input is 24 VDC from a power supply (wall outlet). For now, I try to compose it from mostly 5 V sub-systems: SBC relays comms ...
metsik's user avatar
  • 173
3 votes
2 answers
272 views

How deos this clock generator work?

This circuit shows a clock generator, where a capacitor is charged to a certain voltage for half a period (phi opening switches S1 and S2). The same voltage but with negative polarity will be shown to ...
Andrea Toffanin's user avatar
1 vote
2 answers
145 views

How is a Multi-Bit Delta-Sigma Modulator used to toggle the modulus for a Fractional-N PLL?

I'm doing some reading about fractional-N PLL design, and a large part of this reading has been about Delta-Sigma Modulators, a method of producing a binary string to toggle the frequency divider ...
Jack's user avatar
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0 answers
232 views

Mixing Symfonisk high/low-mid output channels

So i've been messing with this issue for a couple of months and it's just that my electronics knowledge isn't reaching far enough. I have a Symfonisk speaker by Ikea, which outputs a low and high/mid ...
Benjamin de Bos's user avatar
0 votes
1 answer
72 views

A novice question about mixed signal IC design

As far as understand, a digital IC like a DSP can be design by RTL methods and by using languages like Verilog and VHDL. And if I'm not wrong, we cannot yet program pure analog chips by using a ...
user1245's user avatar
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0 votes
2 answers
52 views

"analog" /"mixed-signal" Terminology confusion about the definition of some components and systems

I sometimes encounter that ADCs, DACs, PLLs, DC-DC converters and oscillators are called mixed-signal but sometimes they are grouped under the category of analog. Is there a consensus about that?
cm64's user avatar
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1 vote
0 answers
115 views

Pull-ups in a mixed voltage environment

I'm working on a circuit where a 12 VDC line is switched from a USB-powered microcontroller (U1, running at 3.3 V, specs below). I want to ensure that the switch ...
Alex Hajnal's user avatar
  • 1,354
0 votes
1 answer
102 views

Multiple PCB system vs mixed-signal PCB

I'm designing a high-frequency (\$6\,\text{GHz}\$) mixed-signal PCB. The design contains some noise-sensitive RF analog circuitry (mixer, LNA, 12-bit ADC, etc.) as well as some noisy digital circuitry ...
MattHusz's user avatar
  • 1,053
1 vote
2 answers
521 views

What is the role of discrete resistors and capacitors in a motherboard? [closed]

I know the basic function of resistors and capacitors. I know filters, oscillators, one-shot, differentiator/integrator, ADC/DAC, power supplies, etc. But in a motherboard why are there so many ...
Noob_Guy's user avatar
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7 votes
2 answers
764 views

What's the best ground topology for this mixed signal board?

I'm designing a 4 layer mixed signal PCB with sensitive analog circuits and RF-digital circuits. The board have many mechanical constraints so the places of the analog and digital circuits are fixed. ...
Caniko's user avatar
  • 295
2 votes
2 answers
2k views

Ways to multiplex the output of a DAC?

Part searching in microcontrollers, it looks like most small ones have at most one DAC. What is the just way or ways to output multiple slow signals from a microcontroller with at most a single DAC? ...
Ben G.'s user avatar
  • 268
3 votes
3 answers
595 views

How Can the Quantization Noise of an ADC be Measured using the Digital Output?

The ADC quantization noise is the error signal generated by rounding the sampled analog values of signal. Suppose that we have the digital output of an ADC, how can we measure the quantization noise, ...
Alex L's user avatar
  • 302
0 votes
2 answers
108 views

Signal fidelity from fiber optic crosstalk

I was watching a video about tapping fiber optic cables when it brought up some points from an early US govt document describing security concerns about fiber optic cables. The relevant part: ...
Indigenuity's user avatar
2 votes
2 answers
868 views

Parasitic insensitive switched capacitor circuit

I'm trying to simulate the parasitic insensitive switched capacitor circuit shown here: I am using cadence virtuoso. My input is a sine wave of 1 V amplitude, 0 DC and 1 kHz frequency. I am using ...
Sidharth Thomas's user avatar
3 votes
2 answers
95 views

MOSFET capacitance clarification

Two part question here: Are there ways to directly test the input and output capacitance of a MOSFET, Ciss and Coss? Due to internal inductance and capacitance, is it possible for a standalone MOSFET ...
Jaywalk's user avatar
  • 539
1 vote
1 answer
125 views

Where to place RF shield

I'd like to put a pump drive circuit similar to the one shown below on the same PCB that has two I2C devices, a GPS module, seven analog signals, an ESP32 MCU transmitting WiFi via a trace antenna, ...
YNGVV's user avatar
  • 195
3 votes
0 answers
193 views

Reducing the offset voltage of a source follower

I am currently trying to reduce the offset voltage of the circuit attached below to less than +/- 2mV over a 1V to 4V input range. I have a few constraints for this task: I can use ...
Oreoluwa Adesina's user avatar
1 vote
1 answer
208 views

5VDC and 10VAC on the same PCB - what happens on 10V goes to 5V ground?

Me and a colleague (we are both EE-trainees) had a chat the other day about mixed voltages on the same PCB. She pointed out an interesting question that I was not able to solve. Imaging having a PCB ...
bos's user avatar
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0 votes
1 answer
73 views

Can you make an electric gamma ray emmiter by adding up frequencies with freq. mixers up until you reach gamma ray herz quantities?

I just thought this up. Theoretically if you can add freq numbers you can get to large quantities like in a calculator, only this time mixing electric frequencies using amounts of circuitry right? Is ...
A Federico Osuna Hdez's user avatar
0 votes
1 answer
74 views

Mixed digital/analog rails and level-shifting components best practices

I am designing a board with a ±2.5V analog domain and a 3.3V digital domain where space is at a premium. Digital and analog grounds only connect at a single point near the supplies. As such I am using/...
Edgar Brown's user avatar
  • 8,476
1 vote
1 answer
336 views

Crossing ground planes with low current low frequency signals

I have a board which has two ground planes, analog and digital, that on this board are completely separate. The grounds connect on another board, which is connected via a flat cable. All signals on ...
Timo's user avatar
  • 1,259