AFM907N low Output power

[Anish_V]

Hello,

I am using AFM907N as PA for my design. 2 Section LC Matching has been done for 136-174MHz band. Operating voltages are as follows; Vd=7.5V and Vg=2.8V (Idq=100mA). Feedback stability network (R=100ohms in series with C=1000pF) is added for stability of the device. Overall gain is 16dB across the band with (S11, S22)>20dB. When I try to increase my RF input it is found to be linear till 34-35dBm, increasing further is leading to a saturated output. I did same on the other board with 3 section LC matching and results found to be similar other than gain change where on this board I have slightly higher gain of 18dB.

Could you help me with my design as my requirement is to have linear output power of 38.5dBm across the band. With increase in stability network R value device is able to deliver high gain but still linear output power is around 34-35dBm.

We have even tried to replicate the 800Mhz band reference circuit and found it to be unstable. Adding stability network resolved the stability issue but still the linear output power we could get is around 36dBm.

So kindly provide few suggestions to improve the overall output power

Thanks & Regards,

Anish

[diazmarin09]

Hello Anish,

Datasheet specifies performance of 350-520MHz reference design at Idq=200mA.  Figure 7 from datasheet shows the gain >17dBm at low signal and 350MHz.

I am afraid that we do not have more information regarding the performance of the device at such gain (38.5dBm).

Have you tried to use the ADS model for simulate such requirement?

As far as I know, to provide maximum power over the whole frequency band, the load matching circuit should consist of two (as in NXP reference design) or three LC stages to allow optimizing performance at several frequencies.

Regards,

David

[Anish_V]

Hi,

I have added stability network to all my designs to make AFM907N stable across the band of operation but it is leading to low output power (34dBm). It would be grateful if you Could kindly provide all the design files of AFM907N (136-174MHz, 400-470MHz and 800-890MHz bands) available in RF circuit collection page of NXP website. I have tried requesting from the same page but I couldn't get any support.

Thanks & Regards,

Anish 

[diazmarin09]

Hello Anish,

Note that the webpage contains only the available reference designs.

Are these reference designs useful for you? Have you created a NXP account?

If you are interested in such reference designs and you are not able to download them, please submit a new case to provide them to you.

Regards,

David

[diazmarin09]

You can also find reference desings from the link below:

RF Circuit Collection

Regards,

David