Power Amplifier for BPSK modulation

Jane,

ALM2403-Q1 seems like a good place to start. 

Hi Jane, 

As Ron pointed out, ALM2403-Q1 or similar power amplifiers can certainly meet the modulation requirements. 

I was wondering if you are referring to Powerline Communication (PLC) Application, such as AFE032 or AFE031 product. For 500kHz BPSK modulation, AFE032 will definitely meet your requirements. 

https://www.ti.com/lit/ug/sbou223/sbou223.pdf?ts=1621533145662&ref_url=https%253A%252F%252Fwww.google.com%252F

If the application is driving 50 Ohm resistive load only,  AFE031 may work as well. 

If you have additional questions, please let us know. 

Best,

Raymond

Hello, thanks for the reply. Do you have any suggestions how I implement it? I tried ALM2403-Q1 with a Class E topology and it's distorted. It is not for PLC by the way, I want to use it for telemetry.

Hi Jane,

I would try a linear BPSK design approach, which it will have less distortion at the output. User ALM2403-Q1, ALF032 or similar power amplifiers to drive the 50Ω impedance load. To be frank, I have not tried the modulation method, but it does not seem difficult from what i saw from the link below. 

wireless.org.uk/moritz.htm 

AFE032 and/or AFE031 are integrated PLC ICs. It is an option to use these, even though your application may not require all the features presented in the IC. Alternatively, you may use line driver, such as THS6222 or OPA521 etc.. Most of our PLC communication modulation are using BFSK or OFMD methods. 

THS6222 is part our High Speed Broadband PLC driver, which is design to drive 50Ω impedance load (it is supported by High Speed Op Amp Team). THS6222 can drive differentially input and output. Narrowband PLC (AFE03x) and/or OPA521 are supporting products, which  the power amplifier is designed to drive the load in singled-ended mode.  

What amplitude are your driving per your BPSK application? I'd like to know your load current requirements up to 500kHz. We have many other high current amplifiers can meet this requirements.

slaa681a.pdf

Best,

Raymond

Hey Raymond, I think he said he was trying to drive +/-20V into 50ohm or 400mA peak at gain of 10

I had looked for a 50V supply 400mA output with at least 10MHz GBP and found nothing, there was a TLE part that came up but you also need quite a lot of slew rate at his 500kHz number. Ideally, a 50V current feedback part, but don't know of one, I can say lab testing on the THS3491 showed it would actually operate to 50V supplies, but not supported by process specs. and way too fast for this. 

Hi Michael,

My bad. Jane posted the figure in the first message and I did not look. 

I need is an output power stage that can drive a 50 ohm load and amplify the BPSK signal by at least 20 dBm.

According to his 20dBm, his output stage only requires at least 0.1W to drive 50Ohm load, which is approx. +/-2.24Vpp, which is sort of in agreement with his plot BPSK output plot. 

Best,

Raymond

Hello Raymond,

I tried THS6222 and it did not reach at least 0.1 W. I just downloaded the tina file from here. Or perhaps did I do something wrong?

"According to his 20dBm, his output stage only requires at least 0.1W to drive 50Ohm load, which is approx. +/-2.24Vpp, which is sort of in agreement with his plot BPSK output plot. "

In response to this, I actually tried directly connecting the signal to a 50 ohm resistor and then connecting it to ground. But using the power meter in Tina I cannot seem to make it work. So I thought maybe I cannot directly connect.

Hi Jane

You are running the device in shutdown mode. For full-bias you will need to set BIAS-1 & BIAS-2 to 0V. The gain of the ref design is configured at 10.1 V/V, as shown below. 

If you are interested to use THS6222 line driver, the HS op amp team is the best technical support. 

Best,

Raymond