[Yao-Chin, Yuhang]
Frequency from DDS with -6.5dBm sent to input LO & RF ports of demodulator (ZFMIQ-70D). The demodulator output I & Q ports connected low pass filter of DC-2.5MHz. We measured the Vpp and phase difference of I & Q ports from oscilloscope.
Note: Unbalance Amplitude (dB)= 20* log (Vpp of I port/ Vpp of Q port)
(I) Fixed LO port frequency of 78 MHz
(II) Fixed difference frequency of 100 Hz between LO and RF ports tune range from 66 to 80 MHz.
LO
(MHz)
|
RF
(MHz)
|
Vpp of I
(mV)
|
Vpp of Q
(mV)
|
Unbalance Amplitude
(dB)
|
Phase Difference btw I&Q
(degree)
|
66.0001
|
66
|
260
|
260
|
0
|
91.2
|
67.0001
|
67
|
262
|
260
|
0.07
|
90.1
|
68.0001
|
68
|
266
|
260
|
0.20
|
90.9
|
69.0001
|
69
|
266
|
260
|
0.20
|
90.6
|
70.0001
|
70
|
270
|
260
|
0.33
|
90.7
|
71.0001
|
71
|
272
|
260
|
0.39
|
90.9
|
72.0001
|
72
|
274
|
260
|
0.46
|
90.9
|
73.0001
|
73
|
276
|
259
|
0.55
|
90.6
|
74.0001
|
74
|
278
|
258
|
0.65
|
89.8
|
75.0001
|
75
|
281
|
258
|
0.74
|
90.2
|
76.0001
|
76
|
282
|
258
|
0.77
|
90.2
|
77.0001
|
77
|
282
|
255
|
0.87
|
90.6
|
78.0001
|
78
|
286
|
254
|
1.03
|
90.4
|
79.0001
|
79
|
286
|
254
|
1.03
|
90.1
|
80.0001
|
80
|
286
|
251
|
1.13
|
90.9
|
* Phase: Q=I+90o for LO>RF, Q=I-90o for LO<RF