BC352239A Datasheet, PDF (30/116 Pages) List of Unclassifed Manufacturers – BlueCore 3-Multimedia External

Description of Functional Blocks
6 Description of Functional Blocks
6.1 RF Receiver
The receiver features a near-zero Intermediate Frequency (IF) architecture that allows the channel filters to be
integrated on to the die. Sufficient out-of-band blocking specification at the Low Noise Amplifier (LNA) input
allows the radio to be used in close proximity to Global System for Mobile Communications (GSM) and Wideband
Code Division Multiple Access (W-CDMA) cellular phone transmitters without being desensitised. The use of a
digital Frequency Shift Keying (FSK) discriminator means that no discriminator tank is needed and its excellent
performance in the presence of noise allows BlueCore3-Multimedia External to exceed the Bluetooth
requirements for co-channel and adjacent channel rejection.
6.1.1 Low Noise Amplifier
The Low Noise Amplifier (LNA) can be configured to operate in single-ended or differential mode. Single-ended
mode is used for Class 1 Bluetooth operation; differential mode is used for Class 2 operation.
6.1.2 Analogue to Digital Converter
The Analogue to Digital Converter (ADC) is used to implement fast Automatic Gain Control (AGC). The ADC
samples the Received Signal Strength Indicator (RSSI) voltage on a slot-by-slot basis. The front-end LNA gain is
changed according to the measured RSSI value, keeping the first mixer input signal within a limited range. This
improves the dynamic range of the receiver, improving performance in interference limited environments.
6.2 RF Transmitter
6.2.1 IQ Modulator
The transmitter features a direct IQ modulator to minimise the frequency drift during a transmit timeslot, which
results in a controlled modulation index. Digital baseband transmit circuitry provides the required spectral
shaping.
6.2.2 Power Amplifier
The internal Power Amplifier (PA) has a maximum output power of +6dBm allowing BlueCore3-Multimedia
External to be used in Class 2 and Class 3 radios without an external RF PA. Support for transmit power control
allows a simple implementation for Class 1 with an external RF PA.
6.2.3 Auxiliary DAC
An 8-bit voltage Auxiliary DAC is provided for power control of an external PA for Class 1 operation.
6.3 RF Synthesiser
The radio synthesiser is fully integrated onto the die with no requirement for an external Voltage Controlled
Oscillator (VCO) screening can, varactor tuning diodes, LC resonators or loop filter. The synthesiser is
guaranteed to lock in sufficient time across the guaranteed temperature range to meet the Bluetooth v1.2
specification.
6.4 Clock Input and Generation
The reference clock for the system is generated from a TCXO or crystal input between 8 and 40MHz. All internal
reference clocks are generated using a phase locked loop, which is locked to the external reference frequency.
BC352239A-ds-001Pc
© Cambridge Silicon Radio Limited 2004
Production Information
Page 30 of 116