PRELIMINARY
CYW43438
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
synchronization algorithm.
7.2.7 Receiver Signal Strength Indicator
The radio portion of the CYW43438 provides a Receiver Signal Strength Indicator (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.
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 CYW43438 uses an
internal RF and IF loop filter.
7.2.9 Calibration
The CYW43438 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 transpar-
ently 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 Number: 002-14796 Rev. *K
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