U2790B-MFP Atmel, U2790B-MFP Datasheet - Page 12

• Manufacturer Part Number: U2790B-MFP
• Description: IC QUADRATURE MOD 1000MHZ 16SOIC
• Manufacturer: Atmel

Specifications of U2790B-MFP

• Function: Modulator
• Lo Frequency: 100MHz ~ 1GHz
• Rf Frequency: 100MHz ~ 1GHz
• Noise Floor: -132dBm/Hz
• Output Power: -1dBm
• Current - Supply: 37mA
• Voltage - Supply: 4.5 V ~ 5.5 V
• Test Frequency: 900MHz
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• P1db: -

Figure 19. Demo Board Layout
Application Notes
Noise Floor and Settling
Time
Baseband Coupling
12
U2790B
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
ground in the shortest possible way.
The settling time has to be considered for the system under design. For GSM applica-
tions, a value of C
capacitance does not have any influence on the noise floor within the relevant GSM
mask. For mobile applications the mask requirements can be achieved very easily with-
out C
A significant improvement of the wide-off noise floor is obtainable with C
100 nF. Such values are recommended for applications where the settling time is not
critical such as in base stations. Coupling capacitors for LO
impact on the settling time. The values used for the measurements are CLO
and C
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 2.5 V±
0.15 V.
Figure 19 shows the baseband input circuitry with a resistance of 3.2 kW for each asym-
metric 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 ± 0.15 V.
PU
RFo
.
= 1 nF.
PU
= 1 nF defines a settling time, t
PU
should be connected from Pin 6 to
sPU
, equal or less than 3 ms. This
i
and RF
O
also have a certain
PU
4583A–CELL–01/03
greater than
i
= 100 pF