User's Manual

9/29/2004 OV4F2
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User Manual BCM2035
04/23/03
Broadcom Corporation
Document 2035-UM100-R BCM2035 Radio Transceiver Page 7
TRANSMITTER PATH
The BCM2035 features a fully-integrated zero IF transmitter. The baseband transmit data is digitally GFSK
modulated in the modem block and up-converted to the 2.4 GHz ISM band in the Transmitter Path. The
Transmitter Path consists of signal filtering, I/Q up-conversion, output power amplifier (PA), and RF filtering.
Power Amplifier (PA)
The fully-integrated PA provides a maximum output signal level of +7 dBm using a highly linearized,
temperature compensated design. This gives the user greater flexibility and options in the type of front-end
matching and filtering to use with the
BCM2035. Due to the linear nature of the PA, combined with the fully-
integrated filtering, no external filters are required for meeting Bluetooth and regulatory harmonic and spurious
requirements. For integrated mobile handset applications where the Bluetooth is integrated next to the cellular
radio, minimal external filtering can be applied to achieve near thermal noise levels for spurious and radiated
noise emissions.
The PA supports a power offset that can be set to one of four maximum output power levels in 2 dB increments.
In addition, 24 dB of power control in 2 dB steps is supported for power control functions.
RECEIVER PATH
The Receiver Path uses a 2 MHz low IF scheme to down-convert the received signal for demodulation in the
digital demodulator and bit synchronizer. The Receiver Path provides a high degree of linearity, an extended
dynamic range, and high order on-chip channel filtering to ensure reliable operation in the noisy 2.4 GHz ISM
band. The on-chip filtering enables the
BCM2035 to be used in most applications with no off-chip filtering. For
integrated handset operation where the Bluetooth function is integrated close to the cellular transmitter,
minimal filtering is required to eliminate the desensitization of the receiver by the cellular transmit waveform.
Receiver Signal Strength Indicator (RSSI)
The radio portion of the
BCM2035 provides an RSSI signal to the baseband so that the controller can take part
in a Bluetooth power-controlled link by providing a metric of its own receiver signal strength to determine
whether the transmitter should increase or decrease its output power.
LOCAL OSCILLATOR GENERATION
Local Oscillator (LO) generation provides fast frequency hopping (1600 hops/second) across the 79 maximum
available channels. The LO generation sub-block employs a proprietary architecture for high immunity to LO
pulling during PA operation.
The
BCM2035 uses an external RF and IF loop filter. The RF loop filter uses the different values depending
on the reference frequency or crystal being used. The BCM2035 Data Sheet has recommendations for the
external RF and IF loop filter topology and component values.