BC352239A Datasheet, PDF (47/116 Pages) List of Unclassifed Manufacturers – BlueCore 3-Multimedia External

Device Terminal Descriptions
8.1.6 Single-Ended Input (RF_IN)
This is the single ended RF input from the antenna. The input presents a complex impedance that requires a
matching network between the terminal and the antenna. Starting from the substrate (chip) side, the input can be
modelled as a lossy capacitor with the bond wire to the ball grid represented as a series inductance.
The terminal is DC blocked. The DC level must not exceed (VSS_RADIO -0.3V to VDD_RADIO + 0.3V).
BlueCore3-Multimedia External
L1
1.5nH
RF_IN
R1
6.8Ω
C1
0.68pF
Figure 8.10: Circuit RF_IN
Note:
Both terminals must be externally DC biased to VDD_RADIO.
8.1.7 Transmit RF Power Control for Class 1 Applications (TX_PWR)
An 8-bit voltage DAC (AUX_DAC) is used to control the amplification level of the external PA for Class 1
operation. The DAC output is derived from the on chip band gap and is virtually independent of temperature and
supply voltage. The output voltage is given by:
V_DAC
=
MIN_{⎜⎜⎝⎛}
⎜⎛ 3.3v
⎝
×
CNTRL _ WORD
255
⎟⎞, (VDD
⎠
_
PIO
−
0.3v )_{⎟⎟⎠⎞}
Equation 8.1: Output Voltage with Load Current ≤ 10mA
for a load current ≤10mA (sourced from the device).
or
V_DAC
=
MIN_{⎜⎜⎝⎛}
⎜⎛
⎝
3.3v
×
CNTRL _ WORD
255
⎟⎞, VDD
⎠
_
PIO _{⎟⎟⎠⎞}
Equation 8.2: Output Voltage with No Load Current
for no load current.
BlueCore3-Multimedia External enables the external PA only when transmitting. Before transmitting, the chip
normally ramps up the power to the internal PA, then it ramps it down again afterwards. However, if a suitable
external PA is used, it may be possible to ramp the power externally by driving the TX_PWR pin on the PA from
AUX_DAC.
TX Power
M odul ati on
BC352239A-ds-001Pc
t_carrier
Figure 8.11: Internal Power Ramping
© Cambridge Silicon Radio Limited 2004
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