Hochschule Kempten      
Fakultät Elektrotechnik      
Interface Electronics       Fachgebiet Elektronik, Prof. Vollrath      

Interface Electronics


Prof. Dr. Jörg Vollrath


Video 1. lecture

Länge: 01:06:27
0:0:0 Interface Electronics

0:0:51 Laboratory overview

0:1:54 Web page report

0:2:26 Lecture overview

0:4:48 Prof. Joerg Vollrath

0:4:52 Problems and solution

0:5:52 Solutions

0:6:53 Work in industry, Siemens, Infineon, Qimonda

0:9:48 Arduino ADC, DAC

0:11:1 Trade Fairs

0:11:48 Motivation digital information

0:14:10 Plan for this lecture

0:15:2 Literature, Books

0:16:58 CMOS Analog circuit design Holberg

0:17:58 Manufacturers

0:19:22 Arduino MKR Wifi 1010

0:24:19 Minimum and maximum code and voltage

0:28:58 Sample rate

0:30:46 Arduino project documentation

0:33:28 Extension boards Digilent AD2, DA2

0:35:8 Recording the timeline, time estimation

0:36:58 Take your own notes

0:37:50 Properties of digital signals

0:38:45 Analog and digital signal

0:41:3 LSB and fs sampling frequency

0:42:48 Digital to analog converter metric

0:45:13 Example, Vref, LSB accuracy,

0:49:18 Vmax

0:51:33 Offset error, gain error

0:53:33 Offset error, gain error in graph




  • Prof. Dr.-Ing. Jörg Vollrath
    Sprechstunde: T227 Mi 10:00-10:45
    Please give advanced notice via email
  • Interface Electronics
    • Lecture 2 SWS: Mi 11:45 - 13:15 T129/130
    • Laboratory 2 SWS: Mo 14:00-17:15 T219b
    • 30% Laboratory: Report
    • 70% Exam: 90 min written Exam
      • Non programmable calculator
      • Open book

Memory Products 64M..2G Bit DRAM



What about you?
German and International Students


Important Events

weltleitmesse für innovative elektronikfertigung, München
electronica 2020
components / systems / applications
embedded world Conference
?? 2021, Nürnberg, Germany
Allgäuer Hochschulmesse,
2021, Kempten

Motivation: Data converters


  • Motivation
    • Scaling of analog and digital circuits
    • Applications
  • DA, AD converter blocks, metrics and testing
    • N, Vref, Vfs, Vmax, LSB, fmax
  • LTSPICE: DAC, ADC model
  • Static and dynamic characteristics
    • INL, DNL, offset, gain error
    • Histogramm testing
    • Spectrum, signal to noise ratio, FFT, SNDR
  • DAC architectures
    • Resistor string DACs
    • Charge scaling DACs
    • R-2R type DACs
    • Current based DACs
    • Segmented DACs
  • ADC structures
    • Slope type converters
    • Successive approximation (SAR)
    • Flash
    • Pipeline
    • Oversampled ADCs
  • Challenges in data converters


CMOS: Circuit Design, Layout, and Simulation,
Revised Second Edition, R. Jacob Baker, Wiley,
ISBN 978-0-470-22941-5, Revised 2nd Edition, 2008.
CMOS: Mixed-Signal Circuit Design, Second Edition, Baker, Wiley 2009


Data Conversion Handbook (Analog Devices)
Walter Kester
64 Euro
Data Conversion Handbook pdf


EE247 Analog-Digital Interface Integrated Circuits
Instructor: Haideh Khorramabadi

Murmann, Stanford
EE315B - VLSI Data Conversion Circuits
Course Description EE247
Architectural and circuit level design and analysis of integrated analog-to-digital and digital-to-analog interfaces in modern CMOS and BiCMOS VLSI technology.
Analog-digital converters: Nyquist and over-sampled, digital-analog converters, sample/hold amplifiers, continuous-time and switched-capacitor filters.
Low power mixed signal design techniques.
Data communication systems including interface circuitry.
CAD tools for analog design for simulation and synthesis.


CMOS Analog Circuit Design
Philip Allen, Douglas Holberg
2nd Edition of the book has data converters.
Some editions don't have data converters.

Online References

Practical Training 2020

  1. Guided laboratory 1,2: Webpage report, LTSPICE and data converters
  2. Laboratory 3: Simulating an ADC DAC test setup
  3. Laboratory 4: Setting up the Arduino MKR WIFI 1010
  4. Open: Building and measuring a R2R DAC
  5. Open: Building and measuring a PWM DAC

Final report -> Grading


Design of a system needs data converter components for signal generation and verification measurements.

What effort (time, money) is needed to realize a measurement of a signal or a generation of a signal with a certain accuracy/resolution and speed?

Integrated Systems: Oscilloscope, arbitrary waveform generator, Electronic Explorer

DAC, ADC systems: Evaluation board with ADC, DAC and FPGA or microprocessor

DAC, ADC circuit: How to design a low cost, high performance ADC or DAC?

Analog Digital Interface Circuits

Example Arduino MKR WIFI 1010

  • 1 DAC pin, 6 ADC pins,
  • Digital PWM pins
  • Number of bits: 8..10 bits
  • Sampling rate:

Analog Calibration

  • Connect pin to gnd
  • Connect pin to vdd
Arduino ADC, DAC project

Minimum value of ADC: 0
Maximum value of ADC 1021
Minimum voltage: 30 mV
Maximum voltage: 3.31 V
Sampling rate: 289.28 Hz

Analog versus digital electronic

Digital Circuits Analog Circuits
  • Shrinking of transistor feature size is easy
    Moores Law
  • Digital circuits can be easily built with CMOS transistors
  • Digital signals can have arbitrary precision
  • Automated design
  • Digital circuits are felxible and functions can be easily programmed
  • Precision needs high power, voltage or currents to control signal to noise ratio
  • Precision needs large transistors with well controlled geometry
  • Carefully handcrafted design
  • Analog circuits are very specialized for a certain function
More and more circuits are realized with digital circuits.
Analog circuits are getting more convenient for user and more complex for designer.
Digital offset and gain adjustment and digital filters for compensation.

Properties of digital signals

  • Resolution
  • Frequency
  • Power consumption
  • Price
  • Architecture, type
  • Power supply voltage
  • Input range
  • Manufacturing process feature size
The green analog curve is discretized in time and level resulting in the red points.
The smallest difference in level is called delta Δ or LSB (least significant bit).
The smallest difference in time is called sampling time (ts).

Data converter application

A graph with x axis resolution and y axis frequency shows applications.

Data converter application: software defined radio SDR

A tuneable filter provides a limited bandwidth to an ADC. The radio protocol (WiFi, Bluetooth, FM, AM, digital-TV,LTE) is realized in the digital signal processing block.

Data converter application: Mobile phone


Number of data converters:
HSDP, LTE, UMTS, WLAN, bluetooth
motion, pressure, proximity sensor
speaker, microphone
display control

Digital to analog converter metric

  • N inputs:
    digital signals D0..DN-1
    for simplicity representing positive binary numbers 0..(2N-1)
    D0 is the least significant bit LSB
    DN-1 is the most significant bit MSB
  • Analog output signal:
    for simplicity voltage
    Current and range can be adjusted by additional analog circuits (amplifier, level shifter).
  • Metrics:
    N: number of Bits
    Vref: reference voltage
    Vmax=VFS: maximum, full scale voltage
    Δ , LSB minimum step size
\[ \Delta = \frac{V_{ref}}{2^N} \] \[ N = log_2 \frac{V_{ref}}{\Delta} = ld \frac{V_{ref}}{\Delta} \] \[ V_{max} = V_{ref}- \Delta \]
Binary weighted inputs:
\[ V_O = V_{ref} \sum_{i=0}^{N-1} \frac{D_{i}}{2^{N-i}} \] \[ V_O = \Delta \sum_{i=0}^{N-1} D_{i} \cdot 2^{i} \]

Digital to analog converter transfer characteristic

Table: ideal 2 bit DAC
0 00 0
1 01 0.5
2 10 1
3 11 1.5


\( LSB = \frac{V(11)-V(00)}{2^{N}-1} \)
Offset error: Voffset = V(00) = 0.2 V
Gain error: Vgain = \( \frac{V(11)_{real} }{ V(11)_{ideal} } = 1.1 \)

The points are the generated measurable values. The straight line only interpolates these values to show a linear relationship of the values.


Making of a web report