BC41B143A-DS-001PE Datasheet, PDF (52/102 Pages) List of Unclassifed Manufacturers – BlueCpre 4-ROM Single Chip Bluetooth v2.0 System with EDR

Device Terminal Descriptions
10.1.2 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).
BlueCore4-ROM
L1
1.5nH
RF_IN
R1
6.8Ω
C1
0.68pF
Figure 10.2: Circuit RF_IN
Note:
Both terminals must be externally DC biased to VDD_RADIO.
10.1.3 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 10.1: 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 10.2: Output Voltage with No Load Current
for no load current.
BlueCore4-ROM 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.
BC41B143A-ds-001Pe
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© Cambridge Silicon Radio Limited 2005
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