AK1573 Datasheet, PDF (36/42 Pages) Asahi Kasei Microsystems – Low Noise Integrated VCO

[AK1573/AK1573B/AK1573C]
16. Application Note
Differential to single-ended circuit
AK1573 has differential output ports. “15 Recommended External Circuits” shows single-ended output
but users can convert differential output to single output using lumped element balun. By doing this,
AK1573 outputs higher signal level compared to single-ended output with the same current
consumption. Lumped element balun shows frequency dependence, so users need to populate
optimized elements in order to obtain good matching characteristics. Table.2 shows the reference values
of lumped element balun.
VDD
AK1573
R10
RFOUT_N
C21
L11
C22
Signal Output
RFOUT_P
R11
C20
L12
L10
VDD
Figure 30 Lumped Element Balun Circuit
Table.2 Reference values of lumped element balun
Frequency Range C20
C21
C22
L10
L11
L12
R10
R11
[MHz]
[pF]
[pF]
[pF]
[nH]
[nH]
[nH]
[Ω]
[Ω]
2150 to 2250
2000 to 2150
1900 to 2000
1770 to 1900
1600 to 1770
1450 to 1600
1280 to 1450
1050 to 1280
800 to 1050
550 to 800
350 to 550
200 to 350
100 to 200
60 to 100
40 to 60
30 to 40
1
1
1000
1
1
330
100
100
1
1
1000
1.5
1.5
330
100
100
1
1
1000
2
2
330
100
100
1
1
1000
2.4
2.4
330
100
100
1
1
1000
3.3
3.3
330
100
100
1
1
1000
4.3
4.3
330
100
100
1
1
1000
5.1
5.1
330
100
100
1
1
1000
7.5
7.5
330
100
100
1
1
1000
10
10
330
100
100
1
1
1000
15
15
330
100
100
1.6
1.6
1000
22
22
330
100
100
4.7
4.7
1000
47
47
330
100
100
8
8
1000
82
82
330
100
100
15
15
1000
150
150
330
100
100
27
27
1000
270
270
330
100
100
39
39
1000
390
390
330
100
100
015009351-E-00
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2015/8