Active load pull tuning system for modulated signal

1. A computer-controlled load pull system for tuning using a modulated RF (radio frequency) signal, including an active load pull tuner, having a test port and an idle port, said tuner comprising:

a slabline having a center conductor, an input and an output port;

an adjustable signal coupler comprising a wave-probe having an input port, an output port, a coupled port and an isolated port;

a first circulator C 1 and a second circulator C 2 , each having a port 1 , a port 2 and a port 3 ;

a remotely controlled electronic tuner comprising a number M of RF switching elements;

an amplifier having an input port and an output port;

RF cables and 50 Ohm characteristic impedance terminations;

wherein

the wave-probe is cascaded with the slabline,

the input port of the wave-probe is the test port of the active load pull tuner,

the coupled port of the wave-probe is connected to port 1 of circulator C 1 ,

port 2 of circulator C 1 is connected to the electronic tuner,

port 3 of circulator C 1 is connected to the input port of the amplifier,

the output port of the amplifier is connected to port 1 of the circulator C 2 , and

port 2 of the circulator C 2 is connected to the output port of the slabline,

and wherein

the isolated port of the wave-probe and port 3 of the circulator C 2 are terminated

with the 50 Ohm characteristic impedance termination.

2. The active tuner of claim 1 ,

wherein

the RF switching elements are PIN diodes.

3. The active tuner of claim 1 ,

wherein

the RF switching elements are Varactors.

4. The active tuner of claim 1 ,

wherein

the RF switching elements are microelectromechanical system (MEMS) varactors or MEMS switched capacitors.

5. The active tuner of claim 1 ,

wherein

the wave-probe is integrated in the slabline.

6. The active tuner of claim 1 ,

wherein

a low pass filter (LPF) is inserted between the coupled port of the wave-probe and port 1 of circulator C 1 .

7. A calibration method for modulated signal for the active load pull tuner of claim 1 , said modulated signal having a center frequency Fo and comprising 2N+1 tones Fi wherein

Fo−N*dF<Fi<Fo+N*dF,

with N≥0, −N≤i≤N and dF being the frequency distance between tones;

said method comprising the following steps:

a) connecting the active tuner to a pre-calibrated network analyzer;

b) initializing all RF switching elements to an OFF state;

c) creating 2 M impedance permutations by switching the RF switching elements between their ON and OFF states and measuring s-parameters at all 2N+1 tones Fi,

d) conditioning and saving matrices [S 11 (Fi)] for 0≤i≤2N, wherein S 11 is a calibrated reflection factor.

8. A modulated signal tuning method performed using the calibration data of claim 7 , comprising

a) entering tuning reflection factor targets Γ(Fi)=Xi+j*Yi and tolerances dX and dY;

b) searching through conditioned data in two passes,

i) pass 1 extracts calibration points satisfying Real part tolerance Xi±dX and saves in a data block {Xi} with the associated RF switching element settings,

ii) pass 2 searches through block {Xi} and extracts calibration points satisfying Imaginary part tolerance Yi±dY with the associated RF switching element settings and saves in a data block {XiYi};

c) searching in data block {XiYi} and selecting a first calibration point Xo, Yo for smallest deviation from targets Xi, Yi;

d) configure the RF switching elements to the setting associated with Xo, Yo.