LLRF for SC Heavy Ion LinearAccelerators

Paper study at USPAS17Qi Chen

IMPCAS and LBNL

Low Level RF block-diagram

Phase / Amplitude Detecting

● I & Q Demodulator

LORF

Some trigonometric equations

Low Level RF block-diagram

Phase / Amplitude Modulation

● I & Q Modulator

LO RF

Some trigonometric equations

How mixer works

● We need new frequency

Ideal Mixer

(Multiplier)

Local

Oscillator

Input

Signal

Output

Signal

How to get 90° phase shift

● When a sinusoidal voltage is applied to either asimple capacitor or inductor, the resultant current thatflows is "in quadrature" with the voltage.

Low Level RF block-diagram

I Value

Q V

alu

e Ampl

itude

Phase

Phase Diagram

I & Q Modulation

● I & Q Modulator

Output

Low Level RF block-diagram