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Reg: HMC900 Single ended Operation

Dear team,

                     We planing to use the HMC900LP5E Programmable Gain LPF for the frequency range of 2Mhz to 15Mhz . Kindly provide solution for below question.

1) Kindly provide a equivalent circuit to operate in single ended mode for 2MHz to 15MHz Freq?

2) Also, provide the  recommended balun transformer for 2MHz to 15Mhz operation.

3) What will be the variable Gain (in dB) range for Single end (50 ohms load) operation?


Surya D S

  • 1)  For single ended operation, you should be able to terminate the unused input and output with 50 Ohms.  Make sure they are AC coupled though.

    2)  We use the Mini-circuits ADT2-1T on the evaluation board

    3)  The gain range should not change when driving SE.

  • Thank you for your reply

    Also,The Mini-circuits ADT2-1T supports from Freq 8 MHz only, can you recommend any balun for 2MHz to 15MHz?

  • Can I suggest you re-check the ADT2-1T datasheet, as it seems to show operation from 400 kHz to 450 MHz.

  • Thanks for the Clarification.

    Also , I have some more question regarding HMC900LP5E, please clarify

    1)  I and Q channel can be programed separately (like setting cutoff freq and Gain separately)?

    2) Suppose if we are planing factory calibrated Clock LPF filter, can i able to set the Gain and Cutoff Freq ?

  • The channels do NOT have independent gain and filter control.  You can however independently enable/disable the channels.

    Yes, you can still set the gain and filter cutoff frequency if ordering a factory calibrated (pre-programmed) part.  See Table 7 for more information. 

    What the pre-programmed part really allows is to have specific filter setting (with +/- 2.5% accuracy) and gain setting by default upon power up, without any SPI writes or calibration clock cycles required.  So if you only need a single filter corner and gain, you do not need to route the SPI lines and clock line to the part; you only need to turn the part on and its ready to go in the pre-programmed setting.

    Additionally, if you need a different filter corner, you can change it with a SPI write on a pre-programmed part, but the accuracy won't be as good +/-5%.  However, you do not need to run a calibration cycle to get the +/- 5%. 

  • Thanks for the reply,

    Was going through datasheet and evaluation schematics of the HMC900LP5E. The CMI supply line in the evaluation circuit is isolated by R39 (Depop). The same CMI supply line is connected to I & Q input lines. kindly clarify whether CMI to be connected to +2.5V or isolated. Also specify the current consumption of CMI / CMO pins. Mention the Digital lines current consumption too.