Query on Power Control and Settling Time – TQP7M9106 PA

RF Solutions RF Power Amplifiers
1

Hi Team,

We are currently using the TQP7M9106 PA in our design and would like to clarify a few points related to power control and power optimization.

Use Case:
Our requirement is to enable the PA only during RF transmission and keep it in a power-down or idle state at all other times to reduce overall power consumption.
At present, VCC and VBIAS are connected together , as recommended in the datasheet.

We would appreciate your guidance on the following:

  1. Power Control Method
  • Is it feasible to control PA power ON/OFF using a load switch on the supply rail to meet this requirement?
  • Are there any concerns or limitations with this approach for the TQP7M9106?
  1. Settling / Turn-On Time
  • Could you please share the typical and maximum settling time of the PA after power is applied?
  • This information will help us define the RF enable timing in firmware.
  1. Hardware Recommendations
  • If any hardware changes are recommended to support dynamic power control (for example, separating V
    2W PA CIRCUIT
    2W PA CIRCUIT940×642 64.4 KB

    CC and VBIAS, sequencing requirements, or additional components), please let us know the details.

Your inputs will be very helpful for us to finalize the power control strategy in our design.

Thanks and regards,
Eswaran M
Hardware Test Engineer

2

Typically pin 18 Iref is used for on/off control of the TQP7M9106. This is preferred and easier than switching the 5V supply rail. Switching on/off speed possible should be <100ns using Iref. I don’t have switching speed data for the TQP7M9106, but this figure is based on similar devices. The Iref pin draws in the region of 20mA, so your switch control needs to have this drive capability.

3

image
image1608×723 186 KB

Hi Chris,

Thanks for the quick response,
In datasheet also mentioned about this but that R8 with ref schematics was not there to control Iref pin.

It could be helpful that if we can get that diagram.

Thank you.

4

Feeding 5V via load switch to Iref pin could be possible for my case ?

Disconnecting R7 from supply rail & connect with an control via 240 Ohms is enough to match our requirement?

5

Yes, that should work OK. I’d also keep the LC network (R1 and C13). you may need to drop the value of C13 dependent on how fast you need to switch on/off.

6

Moving the 240R from R7 to R8 disconnects the Iref pin from the 5V supply, and routes it to the header pin labelled J4 Vref. You can see this on the layout. Schematic attached, but this does not have component values.

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1078282sd.PDF (61.3 KB)

7

Hi Chris,

Thanks for the quick updates.