BC41B143A-DS-003PC Datasheet, PDF (33/94 Pages) List of Unclassifed Manufacturers – BlueCore 4-ROM Plug-n-Go Single Chip Bluetooth v2.0 + EDR System

Description of Functional Blocks
8 Description of Functional Blocks
8.1 RF Receiver
The receiver features a near-zero Intermediate Frequency (IF) architecture that allows the channel filters to be
integrated onto 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 BlueCore4-ROM Plug-n-Go to exceed the Bluetooth requirements for co-channel and adjacent channel
rejection.
For EDR, an ADC is used to digitise the IF received signal.
8.1.1 Low Noise Amplifier
The LNA can be configured to operate in single-ended or differential mode. Single-ended mode is used for Class 1⁽¹⁾
Bluetooth operation; differential mode is used for Class 2 operation.
8.1.2 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.
8.2 RF Transmitter
8.2.1 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.
8.2.2 Power Amplifier
The internal Power Amplifier (PA) has a maximum output power of +6dBm. This allows BlueCore4-ROM Plug-n-Go to
be used in Class 2 and Class 3 radios without an external RF PA.
8.2.3 Auxiliary DAC
An 8-bit voltage Auxiliary DAC is provided for power control of an external PA for Class 1 operation or any other
customer specific application.
8.3 Balun and Filter
The Plug-n-Go device incorporates a balun and filter to provide a 50Ω unbalanced antenna port.
8.4 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 v2.0 + EDR specification.
8.5 Clock Input and Generation
The reference clock for the system is generated from a TCXO or crystal input between 8MHz and 40MHz. All internal
reference clocks are generated using a phase locked loop, which is locked to the external reference frequency.
(1) _{Class 1 operation is not recommended for Plug-n-Go devices and therefore is not recommended for BlueCore4-ROM Plug-n-Go.}
BC41B143A-ds-003Pc
Advance Information
© Cambridge Silicon Radio Limited 2005
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