Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Need a very high frequency PWM controller with variable setpoint/reference

Status
Not open for further replies.

mtwieg

Advanced Member level 5
Joined
Jan 20, 2011
Messages
3,543
Helped
1,255
Reputation
2,516
Reaction score
1,236
Trophy points
1,393
Activity points
26,570
Hello, I'm going to try to make a high-bandwidth class D amp for AM modulating RF amplifiers. For best bandwidth (at least 300KHz), I'm want to use a synchronous buck regulator, with an operating frequency around 2MHz or higher. I need to vary the output voltage setpoint with a control voltage, but most PWM controllers have a fixed setpoint internally, so they won't work. Does anyone know of a high speed controller where the setpoint voltage can be varied? Ideally I'd like something like the UC3824, where all the error amplifier pins are available, but that chip isn't fast enough for my needs. The controller doesn't necessarily need to have current-mode control capabilities.
 

atripathi

Advanced Member level 1
Joined
Dec 2, 2009
Messages
452
Helped
91
Reputation
182
Reaction score
88
Trophy points
1,318
Location
INDIA
Activity points
3,818
For fixed reference controoler, you may want to tweak the feedback voltage to get different o/p? This may work for limited range.
 

mtwieg

Advanced Member level 5
Joined
Jan 20, 2011
Messages
3,543
Helped
1,255
Reputation
2,516
Reaction score
1,236
Trophy points
1,393
Activity points
26,570
For fixed reference controoler, you may want to tweak the feedback voltage to get different o/p? This may work for limited range.
This works when you want to manually adjust the output voltage with a knob or something, but I need it to be voltage-controlled, and I want it to be linear. Also I don't want the closed loop transfer function to change severely over the operating range, so that method won't work for me.

I've found that some controllers have the feature I'm looking for, and it's often referred to as "tracking," like here: http://datasheets.maxim-ic.com/en/ds/MAX1953-MAX1957.pdf
But none of the ones I've found so far operate up to 2MHz. Also I should clarify that I don't need any gate drivers built into the controller. I'm planning on using an external half bridge driver anyways. Also I don't need an internal error amplifier.
 
Last edited:

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top