Specifications

BTA3X Module Specification
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➢ 7. RF Subsystem
7.1 Radio Transceiver
BTA3X RF transceiver is a 2.4GHz-band transceiver for Bluetooth headset applications. There are three main
components at the core of its functionality:
(1). Transmitter
(2). Receiver
(3). Synthesizer
The Baseband Processing Unit supplies the Enable Control signals for each of these functions.
The RX input port and TX output port use the same RF terminal so that an external T/R switch is not necessary.
Only a few matching components are placed outside of the RF terminals.
7.1.1 Transmitter
The RF transmitter is comprised of a LPF, a modulator, and a VGA stage. A baseband DAC feeds the TX
baseband signals which are generated by the baseband modulators. A LPF is implemented to attenuate the
second side-lobe of the signal spectrum and reject unwanted oversampling clock or invalid signals. The LPF
3dB bandwitch can be adjusted via the RF registers. The VGA supplies variable gain with more than 20dB
dynamic range, and can be controlled via the RF register interface.
7.1.2 Receiver
The RF receiver is composed of two parts:
(1). RF front-end
(2). IF part
The RF front-end includes a low-noise amplifier (LNA) and a quadrature mixer. The IF part includes a low-pass
filter(LPF) for out-band filtering, and a variable gain amplifier (VGA) uses the same RF ports as the TX output.
The RX front-end gain can be adjusted so that it reduces the probability of bit errors caused by a poor
signal-to-noise ratio. The quadrature mixer (after the LNA) converts the RF signal to the IF band.