BCM20706 Data Sheet
Integrated Radio Transceiver
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 BCM20706 to be used in most applications
with minimal off-chip filtering. For applications in which the Bluetooth function is integrated close to a cellular
transmitter, external filtering is required to eliminate the desensitization of the receiver by the cellular transmit
signal.
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.
Receiver Signal Strength Indicator
The radio portion of the BCM20706 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.
Local Oscillator Generation
A 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 BCM20706 uses an internal RF and IF loop filter.
Calibration
The BCM20706 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 optimal
performance. Calibration tunes the performance 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.
Internal LDO
The BCM20706 uses two LDOs - one for 1.2V and the other for 2.5V. The 1.2V LDO provides power to the
baseband and radio and the 2.5V LDO powers the PA.
Broadcom®
Bluetooth SoC
May 19, 2016 • 20706-DS202-R
Page 14
BROADCOM CONFIDENTIAL
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