T2802 ATMEL [ATMEL Corporation], T2802 Datasheet - Page 13

• Manufacturer Part Number: T2802
• Description: 2.4 GHz WDECT/ISM SINGLE-CHIP TRANSCEIVER
• Manufacturer: ATMEL [ATMEL Corporation]

Functional Description
Receiver
Transmitter
Synthesizer
Power Supply
4509F–DECT–10/03
The RF signal at RF_IN is fed to an image rejection mixer IR_MIXER with its differential
outputs MIXER_OUT1 and MIXER_OUT2 driving an IF-SAW filter at 110.592 MHz or
112.32 MHz. The IF amplifiers IF_AMP1 and IF_AMP2 with an external IF_TANK and
an integrated RSSI function feed the signal to the demodulator DEMOD working at
f = f
tunning in production an integrated 5-bit digital-to-analog (D/A) converter is provided to
control the on-chip varicap diode.
The transmit data at TX_DATA is filtered by an integrated Gaussian Filter GF and fed to
the fully integrated VCO operating at twice the output frequency. After modulation the
signal is frequency-divided by 2 and fed via a TX/RX SWITCH to the TX_DRIVER. This
bus-controlled driver amplifier supplies typically +3 dBm output power at TX_OUT. A
ramp-signal generator RAMP_GEN, providing a ramp signal at RAMP_OUT for the
external power amplifier, is integrated. The slope of the ramp signal is controlled by a
capacitor at the RAMP_SET pin.
The IR_MIXER, the TX_DRIVER and the programmable counter PC are driven by the
fully integrated VCO (including on-chip inductors and varactors). A 3-bit digital-to-analog
converter is used to pretune the frequency. The output signal is frequency-divided to
supply the desired frequency to the TX_DRIVER, 0/90 degree phase shifter for the
IR_MIXER and to be used by the PC for the phase detector PD (f
Unlimited multislot operation is possible by using the integrated advanced closed-loop
modulation concept based on the modulation compensation circuit MCC.
An integrated bandgap-stabilized voltage regulator for use with an external low-cost
PNP transistor is implemented. Multiple power-down and current saving modes are
provided.
IF
/2 ( » 55 MHz) and finally to an integrated baseband filter BB. For demodulator
PD
= 3.456 MHz).
T2802
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