PRELIMINARY
CYW43438
Major FM Radio features include:
■ 65 MHz to 108 MHz FM bands supported (US, Europe, and Japan)
■ FM subsystem control using the Bluetooth HCI interface
■ FM subsystem operates from reference clock inputs.
■ Improved audio interface capabilities with full-featured bidirectional PCM and stereo analog output.
FM Receiver-Specific Features Include:
■ Excellent FM radio performance with 1 μV sensitivity for 26 dB (S+N)/N
■ Signal-dependent stereo/mono blending
■ Signal dependent soft mute
■ Auto search and tuning modes
■ Audio silence detection
■ RSSI and IF frequency status indicators
■ RDS and RBDS demodulator and decoder with filter and buffering functions
■ Automatic frequency jump
7.2 Bluetooth Radio
The CYW43438 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. It is fully compliant with the Bluetooth Radio Specification and EDR specification and meets or exceeds the
requirements to provide the highest communication link quality of service.
7.2.1 Transmit
The CYW43438 features a fully integrated zero-IF transmitter. The baseband transmit data is GFSK-modulated in the modem block
and upconverted to the 2.4 GHz ISM band in the transmitter path. The transmitter path has signal filters, an I/Q upconverter, an output
power amplifier, and RF filters. The transmitter path also incorporates /4–DQPSK for 2 Mbps and 8–DPSK for 3 Mbps to support
EDR. The transmitter section is compatible with the Bluetooth Low Energy specification. The transmitter PA bias can also be adjusted
to provide Bluetooth Class 1 or Class 2 operation.
7.2.2 Digital Modulator
The digital modulator performs the data modulation and filtering required for the GFSK, /4–DQPSK, and 8–DPSK signal. 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.
7.2.3 Digital Demodulator and Bit Synchronizer
The digital demodulator and bit synchronizer take the low-IF received signal and perform an optimal frequency tracking and bit-
synchronization algorithm.
7.2.4 Power Amplifier
The fully integrated PA supports Class 1 or Class 2 output using a highly linearized, temperature-compensated design. This provides
greater flexibility in front-end matching and filtering. Due to the linear nature of the PAcombined with some integrated filtering, external
filtering is required to meet the Bluetooth and regulatory harmonic and spurious requirements. For integrated mobile handset appli-
cations in which Bluetooth is integrated next to the cellular radio, external filtering can be applied to achieve near-thermal noise levels
for spurious and radiated noise emissions. The transmitter features a sophisticated on-chip transmit signal strength indicator (TSSI)
block to keep the absolute output power variation within a tight range across process, voltage, and temperature.
7.2.5 Receiver
The receiver path uses a low-IF scheme to downconvert 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 front-end topology with built-in out-of-band attenuation
enables the CYW43438 to be used in most applications with minimal off-chip filtering. For integrated handset operation, in which the
Bluetooth function is integrated close to the cellular transmitter, external filtering is required to eliminate the desensitization of the
receiver by the cellular transmit signal.
Document Number: 002-14796 Rev. *K
Page 32 of 101
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