LMH6622: Function generator

Part Number: LMH6622

Hye, currently i was given task to create a 13.56MHz sine wave synthesizer, as i searched thru the internet, i manage to get a design on creating a function generator for  1MHz using this LMH6622, but mine is 13.56MHz , do you by chance have any idea on design of any function generator using any opamp for that range of frequency? Really need help! Thank you very much in advance!

3 Replies

  • Hi Nurfatin,

    can you show the design of your 1MHz sine wave generator?

    I would make the sine wave from a 13.56MHz square wave coming from a quartz oscillator. Connect a RLC low pass filter to the output of this quartz oscillator to form a clean sine wave and amplify this sine wave by a suited OPAmp.

    Kai
  • In reply to kai klaas69:

    well hello Kai, here is the design that I got,   by the way so you mean i have to make two different circuit is it? one for the quartz , and one for transform from square to sine?? im really sorry, im new to this :( really appreciate ur help ! here is the link to the webpage (  )    www.ti.com/.../snoa839.pdf

  • In reply to Nurfatin Basri:

    Hi Nurfatin,

    this sort of oscillator is nice and simple but not very stable. Amplitude and frequency can vary with temperature and supply voltage. So, if you exactly need 13.56MHz, I would take a ready-made quartz oscillator providing a square wave with exactly this frequency. Drive a 7-pole passive LRC low pass filter with the output of this oscillator and you will get very pure sine wave.

    DDS (Direct Digital Synthesis) circuits often have such a low pass filter at their output. Look for such a circuit and modify the corner frequency to you needs.

    Kai