I am trying to use an external PA (MMZ09332B) for my transceiver IC, whose circuit with external components is shown below. I am struggling to understand the importance of the pin Pdc (pin 10). What does Pdc mean and what am I supposed to connect to this pin? I think Pdc is to make sure that proper biasing is applied to both the amplifiers in the PA. The datasheet for the PA says, power down voltage of 0V to 1 V (max) in bias on stage and power down voltage of 1.4 V to 2 V (max) in bias off stage. This is where I am finding it difficult about what to connect at the Pdc pin for the PA IC.

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  • \$\begingroup\$ TBH if i were to design with this IC outside the range of the application circuits , i would probably request some more information from the vendor. \$\endgroup\$
    – Linkyyy
    Apr 10, 2021 at 9:02
  • \$\begingroup\$ Data sheet says power down but very little else. It turns off the output stage which is what you want for a tdma and/or battery powered device. I’d be contacting the manufacturer to more detailed data. \$\endgroup\$
    – Kartman
    Apr 10, 2021 at 10:21

1 Answer 1


The Pdc is connected to Power Down pin (pin 10). My interpretation of the power down functionality, according to the Electrical Characteristics table is:

To power up the PA connect the pin to ground (or up to 1.0v). To power down the PA connect the pin to 1.4v-2.0v.

It's unclear if you can just connect this pin to VCC to turn off the bias, since it's not specified in the absolute maximum ratings. I guess you would need to contact the manufacturer.

Electrical Characteristics table

BTW, if I were you I would also ask the manufacturer about the strange connection on pin 7,8 and 9. They forgot to put the junction dots in the schematic. From the layout it seems like pins 7 and 8 are shorted and connected to C3. While pin 9 is connected to C8/L3 and the supply.

From the schematic and pin names it looks like pins 7, 8 and 9 are shorted internally, but it doesn't make sense to me because if it's true than there is a large stub on the output due to the trace connected to pin 9 until it reaches L3.


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