Have any question?
+1(714)342-0932
help@rahsoft.com
Register Login

Login with your site account

Lost your password?

Not a member yet? Register now

RahsoftRahsoft
  • Home
  • Courses

    About Courses

    • All Courses
    • My Dashboard
    • Enrolled Courses
    • Rahsoft RF Certificate
    Linear RF Power Amplifier (PA) Design Theory and Principles online course – RAHRF562

    Linear RF Power Amplifier (PA) Design Theory and Principles online course – RAHRF562

    $400.00 $300.00
    Read More
  • Company
    • About Us
    • Portfolio
    • Careers
  • Communication
    • Contact
    • FAQs
    • Blog
    • Events
  • Consultation
  • Shop
    • Home
    • Courses

      About Courses

      • All Courses
      • My Dashboard
      • Enrolled Courses
      • Rahsoft RF Certificate
      Linear RF Power Amplifier (PA) Design Theory and Principles online course – RAHRF562

      Linear RF Power Amplifier (PA) Design Theory and Principles online course – RAHRF562

      $400.00 $300.00
      Read More
    • Company
      • About Us
      • Portfolio
      • Careers
    • Communication
      • Contact
      • FAQs
      • Blog
      • Events
    • Consultation
    • Shop

    Blog

    • Home
    • Blog
    • Blog
    • Drawbacks of Direct Conversion Receivers – Even Order Distortion

    Drawbacks of Direct Conversion Receivers – Even Order Distortion

    • Posted by Sanchita Sarkar, Ata Sarrafinazhad, Ahsan Ghoncheh
    • Categories Blog, RF System Design of Receivers, RF Topics, Transmitters & Transceivers - RAHRF409
    • Date October 10, 2022
    • Comments 0 comment

    What are the drawbacks of Direct Conversion Receivers?

    • DC offset is coming from local oscillator leakage. The local oscillator leakage problem causes a large DC offset in the baseband and saturates the baseband circuits. Read more.
    • LO Leakage – Direct conversion receiver emits a fraction of its LO power from its antenna. Isolation is a measure of the leakage, or feedthrough, from one port to another. Read more.
    • Flicker Noise – Flicker Noise is one of the types of noise that occurs in almost all electronic components and is inversely proportional to frequency. If the frequency increases, the flicker noise decreases. Read more.
    • Even Order Distortion

    What is Even Order Distortion?

    Another drawback of designing a direct conversion receiver is Even Order Distortion.Take an example as shown in the above diagram where we have two interferers and a non-linear LNA, so at the output of LNA we will get a component with a frequency of w1 – w2, this component is called the beat component. Interferers are two unwanted signals with high amplitude than the desired signal.

    In the course ‘’RF Design Theory and Principles – RAHRF201’’ we discussed non-linearity and interferers Read here. The output for the non-linear system can be expressed as:

    In this case, w1 and w2 are frequencies of interferes with amplitude A1 and A2, and if we have a non-linear system, we had a different kind of inputs. From this, we are interested in the third part of the second-order non-linearity which gives w1+w2, and w1 – w2.

    Looking back into the example above, the inputs we have are w1 and w2 and at the output, we get the component which comes from the second-order non-linearity whose frequency is w1 – w2. As we know that w1 and w2 are close to each other and therefore the frequency w1 – w2 is a low value, meaning it will go the baseband side and hence would be close to the desired channel.

    There is another path from port 1 to port 3 in the mixer through which it can come close to the desired channel. So this frequency w1 – w2 can pass through the feedthrough and it will appear directly at the output which can cause us the problem corrupting the channel as it’s very close to the baseband. So the question here is how to prevent this problem.

    How to avoid Even Order Distortion?

    For LNA – Use high IIP2 structures. For example, if you have to design an LNA and have a direct conversion receiver then design it in such a way that it has very low IIP2.  Make it a differential LNA as we don’t have second-order non-linearity in a differential system.

    For Mixer – Design it as a differential mixer and be careful about the layout as the Mixer layout should be symmetrical to avoid the feedthrough from ports. The feedthrough will cancel out at the output of the symmeterical mixer.

    Points to note will be:

    • High IIP2 structures (Implies that they should have differential structure)
    • Differential mixer
    • Design symmetrical Mixer layout

     

    Learn more about this topic by taking the complete course ‘RF System Design of Receivers, Transmitters & Transceivers – RAHRF409’. Watch the course videos for more detailed understanding. Also checkout other courses on RF system and IC design on https://rahsoft.com/courses/.
    Rahsoft also provides a certificate on Radio Frequency. All the courses offer step by step approach.

    Tag:direct conversion receivers, Even Order Distortion

    • Share:
    Sanchita Sarkar, Ata Sarrafinazhad, Ahsan Ghoncheh

    Previous post

    Drawbacks of Direct Conversion Receivers – Flicker Noise
    October 10, 2022

    Next post

    Calculate Flicker Noise Penalty with Example
    October 11, 2022

    You may also like

    Screenshot 2023-01-30 at 19.00.34
    What is a Lossless Transmission Line?
    30 January, 2023
    Screenshot 2023-01-27 at 12.10.53
    What is Characteristic Impedance?
    28 January, 2023
    Screenshot 2023-01-24 at 21.47.20
    Transmission Line Phasor equations
    24 January, 2023

    Leave A Reply Cancel reply

    Your email address will not be published. Required fields are marked *

    Search

    Categories

    • Blog
    • RF Design Theory and Principles – RAHRF201
    • RF System Design of Receivers
    • RF Topics
    • Transmitters & Transceivers – RAHRF409
    • Uncategorized

    Latest Courses

    RF Fundamentals,Basic Concepts and Components – RAHRF101

    RF Fundamentals,Basic Concepts and Components – RAHRF101

    $20.00 $12.00
    RF Microwave and Radio Frequency Transmission Theory Online Course – RAHRF200

    RF Microwave and Radio Frequency Transmission Theory Online Course – RAHRF200

    $20.00 $12.00
    RF Design Theory and Principles – RAHRF201

    RF Design Theory and Principles – RAHRF201

    $200.00 $45.00
    logo-rahsoft

    +1(714)342-0932

    help@rahsoft.com

    Courses

    • All Courses
    • My Dashboard
    • Enrolled Courses
    • Rahsoft RF Certificate

    Company

    • About Us
    • Portfolio
    • Careers

    Communication

    • Contact
    • FAQs
    • Blog

    Links

    • Consultation
    • Shop
    • Events

    Copyrights 2021 – Rahsoft

    • Privacy
    • Terms
    • Sitemap

    BECOME AN INSTRUCTOR?

    Join thousand of instructors and earn money hassle free!

    GET STARTED NOW