BCM20705 Datasheet, PDF (14/67 Pages) Cypress Semiconductor – Single-Chip Bluetooth Transceiver and Baseband Processor

BCM20705 Data Sheet
Integrated Radio Transceiver
Section 2: Integrated Radio Transceiver
The BCM20705 has an integrated radio transceiver that has been optimized for use in 2.4 GHz Bluetooth
wireless systems. It has been designed to provide low-power, low-cost, robust communications for applications
operating in the globally available 2.4 GHz unlicensed ISM band. The BCM20705 is fully compliant with the
Bluetooth Radio Specification and enhanced data rate specification and meets or exceeds the requirements to
provide the highest communication link quality of service.
Transmitter Path
The BCM20705 features a fully integrated zero IF transmitter. The baseband transmitted data is digitally
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, a high-output power amplifier (PA), and RF
filtering.
The BCM20705 also incorporates modulation schemes to support enhanced data rates.
• P/4-DQPSK for 2 Mbps
• 8-DPSK for 3 Mbps
Digital Modulator
The digital modulator performs the data modulation and filtering required for the GFSK, /4DQPSK, and 8-
DPSK signals. The fully digital modulator minimizes any frequency drift or anomalies in the modulation
characteristics of the transmitted signal and is much more stable than direct VCO modulation schemes.
Power Amplifier
The BCM20705 integrated PA can be configured for Class 2 operation, transmitting up to +4 dBm. The PA can
also be configured for Class 1 operation, transmitting up +10 dBm at the chip in gFSK mode, when a minimum
supply voltage of 2.5V is applied to VDDTF.
Because of the linear nature of the PA, combined with integrated filtering, minimal external filtering is required
to meet Bluetooth and regulatory harmonic and spurious requirements.
Using a highly linearized, temperature compensated design, the PA can transmit +10 dBm for basic rate and
+8 dBm for enhanced data rates (2 to 3 Mbps). A flexible supply voltage range allows the PA to operate from
1.2V to 3.3V. A minimum supply voltage of 2.5V is required at VDDTF to achieve +10 dBm of transmit power.
Broadcom®
Bluetooth Transceiver and Baseband Processor
November 13, 2014 • MCS20705-DS104-R
Page 13
BROADCOM CONFIDENTIAL