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Loop filter for HMC440 and HMC733 (sythentiser and VCO respectively)

Category: Datasheet/Specs
Product Number: HMC440; HMC733

I refer to the application circuit above from the datasheet of the HMC440 and will like to know the following:

1. I tried the several filters in ADsimPLL and the LT6200 seems to give the best phase noise performance. Is this a good choice of OpAmp or is a design as above limited to the THS4031 opamp as active filter?

2. Instead of the +/-5V for biasing the opamp, can I use a single bias of +10V and GND?

3. Any suggestions of a LDO or regulator that can be used with the opamp?

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  • Hi Obabarin, sorry we didn't get back to your questions in time, were you able to resolve this now? You can let me know and I will respond as soon as possible. In the mean time,

    1. No you are not restricted to THS4031, the LT6200 family are other options you can use in your design as tested in the ADISIMPLL.
    2. From the datasheet, although LT6200 family is characterized at single ended +5v to GND and dual ended +/-5V, it also has a wide operable range of up to 12.6V. So, yes you can use the bias +10V to GND.
    3. You have the option of using the LT3045 or you can connect your output directly but using decoupling capacitors. Both cases have been known to work well. 

  • Thanks for the reply Jude.
    I will keep you posted on my progress.