CYW4343X
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 PA combined with some integrated filtering, exter-
nal filtering is required to meet the Bluetooth and regulatory harmonic and spurious requirements. For integrated mobile handset
applications 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 syn-
chronizer. 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
CYW4343X 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.
7.2.6 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 syn-
chronization algorithm.
7.2.7 Receiver Signal Strength Indicator
The radio portion of the CYW4343X provides a Receiver Signal Strength Indicator (RSSI) signal to the baseband so that the control-
ler 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.
7.2.8 Local Oscillator Generation
Local Oscillator (LO) generation provides fast frequency hopping (1600 hops/second) across the 79 maximum available channels.
The LO generation subblock employs an architecture for high immunity to LO pulling during PA operation. The CYW4343X uses an
internal RF and IF loop filter.
7.2.9 Calibration
The CYW4343X radio transceiver features an automated calibration scheme that is self contained in the radio. No user interaction is
required during normal operation or during manufacturing to optimize performance. Calibration optimizes the performance of all the
major blocks within the radio to within 2% of optimal conditions, including filter gain and phase characteristics, matching between
key components, and key gain blocks. This takes into account process variation and temperature variation. Calibration occurs trans-
parently during normal operation during the settling time of the hops and calibrates for temperature variations as the device cools
and heats during normal operation in its environment.
Document No. 002-14797 Rev. *H
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