User guide

71M6533-DB Demo Board User’s Manual
Page: 37 of 75 ` REV 3
Finally, we calculate the new calibration current gain coefficient, including compensation for a slight gain
increase in the phase calibration circuit.
29
0
9
0
92020
)21()2cos()21(21
))2cos()21(222(2
1
1_
_






Tf
TfPHADJPHADJ
A
ICAL
ICAL
XI
NEW


2.1.2 CALIBRATION WITH FIVE MEASUREMENTS
The five measurement method provides more orthogonality between the gain and phase error derivations. This
method involves measuring E
V
, E
0
, E
180
, E
60
, and E
300
. Again, set all calibration factors to nominal, i.e. CAL_IA =
16384, CAL_VA = 16384, PHADJA = 0.
First, calculate A
XV
from E
V
:
1.
1
VXV
EA
Calculate A
XI
from E
0
and E
180
:
2.
1)cos(1
)0cos(
)0cos(
0



SXIXV
SXIXV
AA
IV
AAIV
E 

3.
1)cos(1
)180cos(
)180cos(
180



SXIXV
SXIXV
AA
IV
AAIV
E 

4.
2)cos(2
1800

SXIXV
AAEE 
5.
)cos(2
2
1800
S
XIXV
EE
AA



6.
)cos(
12)(
1800
SXV
XI
A
EE
A



Use above results along with E
60
and E
300
to calculate 
S
.
7.
1
)60cos(
)60cos(
60



IV
AAIV
E
SXIXV

1)sin()60tan()cos( 
SXIXVSXIXV
AAAA 
8.
1
)60cos(
)60cos(
300




IV
AAIV
E
SXIXV

1)sin()60tan()cos( 
SXIXVSXIXV
AAAA 
Subtract 8 from 7
9.
)sin()60tan(2
30060 SXIXV
AAEE  
use equation 5:
10.
)sin()60tan(
)cos(
2
1800
30060 S
S
EE
EE 



11.
)tan()60tan()2(
180030060 S
EEEE  