CMX994 Datasheet, PDF (46/61 Pages) CML Microcircuits – Local Oscillator

Direct Conversion Receivers
CMX994/CMX994A/CMX994E
8.2 Operation Below 100MHz
The CMX994/CMX994A/CMX994E can be safely used below 100MHz, down to at least 30MHz, however
performance will degrade at lower frequencies and will fall particularly rapidly below 50MHz.
50
30
49
25
48
47
20
46
45
15
44
10
43
42
Gain
5
41
NF
40
0
20
30
40
50
60
70
80
90 100 110 120
Frequency / MHz
Figure 26 Typical Gain and NF Variation of Demodulator Stages at Low Frequencies
The LNA can be matched for 30MHz giving a gain of 15.5dB and noise figure of 5dB. Intermodulation is
typically +3.5dBm.
For a 50MHz application, typical circuit values are shown in Table 18using the circuit of Figure 7. Typical
results using this configuration are shown in Table 19.
C1
1nF
L1
C2
33 pF // 10nF
L2
C3
1nF
L3
560 nH
12 pF (capacitor)
Not Fitted
Table 18 50MHz LNA and Inter-stage Components (100Ω mode)
Parameter
Gain
Noise Figure
IIP3
Result
63.5dB
5dB
-0.5dBm
Table 19 Summary of Results for the Complete Rx Chain at 50MHz
 2015 CML Microsystems Plc
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