DEMOBOARD-U2790B Atmel, DEMOBOARD-U2790B Datasheet - Page 13

• Manufacturer Part Number: DEMOBOARD-U2790B
• Description: BOARD DEMO COM-I/Q MOD 1GHZ
• Manufacturer: Atmel
• Type: Modulatorr

Specifications of DEMOBOARD-U2790B

• Frequency: 1GHz
• Wireless Frequency: 1 GHz
• For Use With/related Products: U2790B
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

8. Application Notes
8.1
8.2
4583D–CELL–07/06
Noise Floor and Settling Time
Baseband Coupling
In order to reduce noise on the power-up control input and improve the wide-off noise floor of the
900-MHz RF output signal, capacitor C
shortest possible way.
The settling time has to be considered for the system under design. For GSM applications, a
value of C
not have any influence on the noise floor within the relevant GSM mask. For mobile applications
the mask requirements can be achieved very easily without C
A significant improvement of the wide-off noise floor is obtainable with C
Such values are recommended for applications where the settling time is not critical such as in
base stations. Coupling capacitors for LO
time. The values used for the measurements are CLO
The U2790B-FP (SO16) has an integrated biasing network which allows AC coupling of the
baseband signal at a low count of external components. The bias voltage is 2.5V ±0.15V.
Figure 7-17
input. The internal DC offset between A and A, and B and B is typically < ±1 mV with a maximum
of ±3 mV. DC coupling is also possible with an external DC voltage of 2.5 ±0.15V.
Figure 8-1.
PU
shows the baseband input circuitry with a resistance of 3.2 k for each asymmetric
= 1 nF defines a settling time, t
Baseband Input Circuitry
Mixer input stage
PU
i
and RF
sPU
should be connected from pin 6 to ground in the
, equal or less than 3 ms. This capacitance does
O
also have a certain impact on the settling
i
= 100 pF and C
PU
3.2 k
.
A
A
,
,
B
B
RFo
PU
= 1 nF.
greater than 100 nF.
U2790B
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