BCM4356 datasheet(21/155 Pages) CYPRESS

21 / 155 page

Document Number: 002-15053 Rev. *D

Page 21 of 155

ADVANCE

CYW4356

4.2.5 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 CYW4356 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.

4.2.6 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.

4.2.7 Receiver Signal Strength Indicator

The radio portion of the CYW4356 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.

4.2.8 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 CYW4356 uses an

internal RF and IF loop filter.

4.2.9 Calibration

The CYW4356 radio transceiver features an automated calibration scheme that is fully self contained in the radio. No user interaction

is required during normal operation or during manufacturing to provide the optimal performance. Calibration optimizes the perfor-

mance of all the major blocks within the radio to within 2% of optimal conditions, including gain and phase characteristics of filters,

matching between key components, and key gain blocks. This takes into account process variation and temperature variation.

Calibration occurs transparently 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.

BCM4356 Datasheet(PDF) 21 Page - Cypress Semiconductor