Questions tagged [mixed-signal]

A circuit which contains both analog and digital signals.

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50 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 ...
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5answers
101 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 ...
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93 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 ...
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1answer
68 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 ...
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1answer
38 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
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1answer
79 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 ...
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16 views

Common Mode voltage for AC coupled mixed signal circuit clocks

I am confused by the wording used in the clock sections of a couple Analog Devices and Texas Instruments datasheets. My main confusion surrounds the use of AC coupled differential clocking. I know ...
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21 views

ADC power plane confusion

I'm working on an ADC design using the ADC12DL080, but I'm a little confused by the datasheet's recommendations for power planes. The device has a 3.3v analog rail, a 3.3v digital rail (which ...
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2answers
95 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 ...
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29 views

Multiplexer and feed-forward equalization capable line driver

Starting this project, on multiplexer and feed-forward equalization capable line driver. Would this be a good implementation for the pre-drivers and drivers or maybe a CML implementation would be more ...
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2answers
58 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 ...
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42 views

Filtering and latching comparator output on STM32

I have an STM32F301, and plan to use the COMP2 to compare a hall sensor against the DAC output to check if a current is under the set limit. Now I'd like to ignore very short bursts from inrush ...
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138 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 ...
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1answer
50 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 ...
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2answers
32 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?
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72 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 ...
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1answer
44 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 ...
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2answers
293 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 ...
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2answers
358 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. ...
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2answers
449 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? ...
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3answers
328 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, ...
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2answers
70 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: ...
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1answer
303 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 ...
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2answers
60 views

MOSFET Capacitance clarification

2 part question here. Are there ways to directly test the input and output capacitance of a MOSFET, Ciss and Coss? On that note, due to internal inductance and capacitance, is it possible for a ...
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1answer
80 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, ...
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0answers
86 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 ...
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1answer
121 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 ...
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1answer
62 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 ...
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1answer
54 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/...
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1answer
241 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 ...
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2answers
99 views

Connecting mixed-speed multiple serial devices to two microcontrollers

I'm trying to figure out the best way to integrate all devices flawlessly on the 8051 based microcontrollers. If each device was the same low speed, then I could multiplex each and every one of them ...
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1answer
2k views

How does a Delta-Sigma DAC work?

I have looked at how the Sigma-Delta ADC works and I understand it. However, it seems to me that there is not a lot of literature about the Sigma-Delta DAC. I want to build a model of it in Simulink....
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3answers
537 views

How to store the difference of 2 voltages on capacitor?

Suppose we have two voltages V1 and V2 how can we store the voltage difference (V1-V2) on a given capacitor? I tried charging the top plate of the capacitor to V1 ...
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49 views

lm13700 as Diode laser voltage to current converter

I generated two Signals, one using dac7611 (ramped signal with fre = 0.04hz ) and the other one, using AD9833 DDS (sin wave with fre = 32 KHz) then generated signals added using ad620an. Is this ...
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1answer
45 views

Mixed-Signal modular system grounding scheme

I'm attempting to create a sensitive, precise mixed signal system (more than 24bit) compose of a backplane and stacked modules on 2.54mm headers.It is multi-channel and channel's modules are well ...
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3answers
1k views

Superimpose a High Frequency AC Small Signal on a DC Power Signal

I am facing a challenging problem with a circuit that I am currently working on, I would like others input and thoughts. I have a DC power signal that I am injecting a AC small signal this mixed ...
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1answer
430 views

How to create a mixed signal pcb

I want to create a board that has both high speed digital components (specifically the SAM3X8E - from arduino DUE) and an analog audio circuit. The analog parts were originally a shield to the ...
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1answer
163 views

Multicard System Grounding

I am building a system with multiple PCB cards. The whole system has a Chassis Ground; connected to a main Power Supply reference. All cards will be powered in reference to Chassis Ground. Each ...
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1answer
100 views

How to split isolated an audio trigger signal for processing by an ADC

I have a problem trying to split a drum trigger signal so that I can process it via an ATXMEGA64A3 microcontroller. The goal is to have the signal going from the trigger to both the existing sound ...
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1answer
317 views

Review of my first ever PCB design for a watering control robot.

I'm building a small watering control for one of my large indoor plants. This is my first real electronics project outside of school. Although I studied EE at university and did my basic component and ...
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1answer
82 views

Understanding mixed-signal PCBs, in most simple sense

I understand that mixed-signal is a circuit that obviously has both analog and digital circuits. I am trying to understand what really would be classified as mixed-signal. If you had a PCB with some ...
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3answers
437 views

Where do I put digital ground in a dual-rail mixed signal circuit?

I'm working on a project for school (a discrete dual-slope ADC) that will combine digital and analog circuitry and operate off of a ±15V dual-rail supply. The "analog ground" will be at 0V, as ...
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1answer
266 views

LOW and HIGH definition for Enable pin of 4051?

Suppose we have connected an X volt (X=10) as the supply of a 4051 MUX (which is active LOW), can we disable the device by applying a B volte (assume B is 5 volt). In other words, how high is HIGH ...
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1answer
1k views

Analog current input to microcontroller ADC [closed]

My project requirement is to make an analog current input to ADC of microcontroller. Analog input current has 4-20mA specification. Since I don't have particular industrial sensor with 4-20mA ...
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3answers
353 views

How to live with noise and ground loops in a system with Electronics, Power Electronics, Electrical Machines, Three-phase power and several boards?

I ask for help with a experimental assembly I am developing in the university, which is a small size power generation plant. The system consists of a DC machine, a induction machine, several current ...
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2answers
266 views

Where should a switching regulator be placed in relation to analog and digital circuitry?

General Layout: I've partitioned a mixed-signal board as follows: The dashed blue line indicates the analog/digital divide, but it is NOT a ground cut. This layout is intended to avoid analog and ...
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2answers
362 views

The right way to mix digital signals

I have a dozen of sources of digital signal, 16-bit signed words. I have implemented very simple mixer where all sample values are summed, and then shifted right to prevent overload. Unfortunately ...
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1answer
3k views

Back to back Schottky diodes between ground connections

In a mixed-signal IC, you most likely will have two ground planes, analog ground and digital ground. This seems fair enough and easily understandable but my real question is: Why would you need to ...
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5answers
410 views

Decoupling capacitors values in mixed-signal circuit

I know theory about decoupling capacitors (ESR, ESl, parallel capcitors etc.) I have read Electromagnetic Compatibility Engineering, H.W. Ott. My question is about practical design. How shall i ...
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1answer
482 views

Mixing two square waves and isolating intermodulation component

I currently have two square wave signals at f1 and f2 (f1 >> f2) that serve as reference signals to two separate lock-in amplifiers that are subsequently connected in cascade to extract the component ...