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Fairchild FSAV430
The FSAV430 (QSOP-16 package) contains 4 SPDT switches with a common control line. Only 2 switches are needed to implement the H-Mode mixer. The PCB layout of the FSAV430 with the 3 TT4-1A transformers is very compact indeed. The FSAV430 does not require an 74AC74 divide by two squarer as it does not need both Q and !Q. However in this test the 74AC74 squarer is used.
The following table summarizes the measurements with the FSAV430:
| FSAV430 + TT4-1A + 74AC74 |
Vdd = 3.3V, Vbias = 1.65V |
Best bias |
| Band |
BPF |
mixer |
MDS -dBm |
IF rej |
spur |
mixer IIP3 (dBm) @ 20KHz spacing |
Bias |
IIP3 |
| IL |
CL |
- |
+ |
|
avg |
-6 |
-3 |
0 |
+3 |
+5 |
|
0 |
| -dB |
-dB |
BPF |
BPF |
-dB |
dB |
dBm |
dBm |
dBm |
dBm |
dBm |
V |
dBm |
| 160 |
3,3 |
5,08 |
132 |
128 |
41,2 |
|
|
|
33,0 |
|
|
1,65 |
33,0 |
| 80 |
1,4 |
5,00 |
133 |
131 |
40,4 |
|
31,3 |
31,6 |
32,3 |
31,3 |
|
1,65 |
32,3 |
| 40 |
2,3 |
5,00 |
133 |
130 |
39,2 |
|
|
|
31,6 |
|
|
1,65 |
31,6 |
| 30 |
3,4 |
5,00 |
133 |
129 |
38,4 |
|
|
|
31,2 |
|
|
1,65 |
31,2 |
| 20 |
3,4 |
5,00 |
133 |
129 |
35,6 |
|
|
|
30,5 |
|
|
1,65 |
30,5 |
| 17 |
3,0 |
5,00 |
133 |
129 |
32,8 |
|
|
|
30,1 |
|
|
1,65 |
30,1 |
| 15 |
3,9 |
5,04 |
133 |
128 |
32,0 |
-4,8 |
|
|
28,9 |
|
|
1,65 |
28,9 |
| 12 |
3,7 |
4,94 |
133 |
129 |
31,2 |
|
|
|
28,3 |
|
|
1,65 |
28,3 |
| 10 |
2,3 |
5,08 |
133 |
129 |
30,8 |
|
|
|
29,2 |
|
|
1,65 |
29,2 |
| 6 |
|
|
|
|
|
|
|
|
|
|
|
|
|
I was not able to do measurements on 6M with this mixer as the 74AC74 on this board failed to operate at those frequencies. (51 + 9) * 2 = 120MHz. The 74AC74M is specified at max 125MHz clock. This was the only mixer that failed on 6M, so it was a poor 74AC74M from that batch.
The FSAV430 is tested at 3.3V Vdd. From the datasheet that contains a graph plotting Ron versus Vin it is obvious that this switch should be biased at the midpoint. Experiments do confirm this. The best bias point is 1.65V.
IP3 measurements showed values around +31dBm. Due to its low Vdd the IP3 was degrading fast at input levels above +3dBm.
The IP3 does not degrade as much at higher frequencies like the other mixers.
The FSAV430 showed very good spur reduction of all mixers tested at average -4.8dB below MDS for 130 spurs on 15M. The FSAV430 sounds really quiet with respect to the spurs, although a number of spurs still remain equally strong.
The RF-IF isolation at 9 MHz is poor when compared with for example the FSAV332 or the FST3125.
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