Magnetic resonance imaging (MRI) systems apply powerful radio frequency (RF) and strong magnetic fields to systematically align the magnetic moment of protons in human tissue. For an MRI system to produce good quality images, the timing and linearity of the RF power subsystem must be precisely controlled. With the peak power of the RF power amplifiers approaching 40 kW, keeping the signal phase accurate to within a few picoseconds is a significant challenge.
Philips Healthcare engineers used Model-Based Design with MATLAB®, Simulink®, and HDL Coder™ to develop an innovative digital RF power subsystem for MRI machines. Implemented in VHDL® and deployed on an FPGA, the subsystem uses digital predistortion and feedback control loops to achieve the required precision and linearity.
“Creating VHDL code is an activity we have to do, but it is not one to which we add much value,” says Mark van Helvoort, senior manager at Philips Healthcare. “Simulink and HDL Coder enable us to focus on developing our algorithms and refining our design via simulation, not on checking VHDL syntax and coding rules.”