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constant power (APC) current driver design

Hi,

I am thinking over current source again in this year. Previously I did current source but I never got into the RF field.

I am wondering how to design a constant power current source with a modulation frequency from DC to 150 MHz?

I saw some circuits with fast DAC to control a line driver to provide up to 0 to 1A analogue current. But the limit is up to 30 MHz.

Right now suppose I need 0 to 1A with 0-150MHz analogue modulation, how to do it? Any design notes or journal paper talked about it? I found little.

To use a RF mosfet with simple feed back from some power sensing monitor or use a VxI chip? impossible since most of this type of chips have bandwidth in kHz level.

Really have no idea now.

Thanks, PB

Reply to
Power boy
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and I suddenly realize that PID is not efficient as in power electronics, the type III bandwidth usually has bandwidth of 20khz, way too slow.

Reply to
Power boy

An emitter-coupled pair with current source on the emitters (an inductor, at high frequency) will steer current effectively, and 1A/150 MHz is not out of the question. You won't like the results if you insist on '0' in the range, that gets into hard base-drive requirements (but you could always leave the transistor turned ON and steal some current...).

Doesn't need to be bipolar, of course, a source-coupled pair of MOSFETs could do something similar.

I'm dubious that the output impedance will be high enough to be 'practically infinite', like a good DC current source.

Reply to
whit3rd

it seems working on open loop only. the feedback is a big issue, at @150MHz need to do feedback to keep constant power output.

Reply to
Power boy

d
t

"constant power" and "current source" are contradictory. You can have one or the other but not both. Which do you want? Mark

Reply to
Mark

did

ist

my misleading, this power is not V*I. current source could be constant power , this power is from the driven object like a laser diode, this power is from the light emission and detected by a photodiode.

Reply to
Power boy

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