u2741b ATMEL Corporation, u2741b Datasheet - Page 5

• Manufacturer Part Number: u2741b
• Description: Uhf Ask/fsk Transmitter U2741b
• Manufacturer: ATMEL Corporation

5. Application Circuit
5.1
4733B–RKE–09/05
Output Power Measurement
The following component values are recommendations for a typical application. C
are block capacitors. The values of these capacitors depend on the board layout. C
C
and f = 1 GHz should be as low as possible.
C
way that the desired transmission frequency deviation is achieved (typical ±30 kHz). The capac-
itance here depends upon the crystal's load capacity (C
the crystal. C
C
the appropriate impedance transformation is possible.
L
can be either printed on the PC board or be a discrete component.
The output network [as shown in
values of L
L
Table 5-1
Table 5-1.
Figure 5-1.
Feed
10
6
3
Loop1
= 1 nF, and C
is not needed in ASK transmitter applications. In the case of FSK, C
and C
is an inductor for the antenna's DC current supply. A typical value is L
and C
433.92
f/MHz
315
10
shows the values for an output power of 2 mW and an R
10
form the transformation network to adopt the output impedance of the IC to 50 .
Loop2
2
and C
= 3.9 nF, C
Transformation Network
Measurement Output Network
7
are selected so that the antenna oscillates in resonance and the adaptation to
= 22 nF are typically used here. For C
10
depend on the layout.
1
= 15 nF, and R
C10/pF
PWRVCC
2.7
1.8
Figure
ANT
5-1] can be used for output power evaluation, the exact
4
= 220 .
50
V
L
C
10
S
10
L10/nH
56
33
4
5
) recommended by the manufacturer of
Z
, the impedance between f = 100 MHz
Load-opt
PWRSET
3
= 1.2 k .
is selected in such a
Feed
Z
260 + j330
185 + j268
Load_opt
= 220 nH. L
U2741B
5
, C
/
6
5
, and C
= 1 nF,
Feed
5
7