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STLC2150

FUNCTIONAL DESCRIPTION

Receiver

from 75

Ω balanced RF input and amplified by an LNA.

The mixers are driven by two quadrature signals which are locally generated from a VCO signal running at

twice the frequency. The output signals in the I signal path and Q signal path are bandpass filtered by a

polyphase bandpass filter for channel filtering and image rejection. The output of the lowpass filters is amplified

by a VGA to the optimal input range for the A/D converters.

Further filtering is done in digital filters. The digital part demodulates the GFSK coded bit stream by evaluating

the phase information in the I and Q signals.

The digital part recovers the receive bit clock. It extracts RSSI data by calculating the signal strength. Overall

automatic gain amplification in the receive path is controlled by the digital part.

Transmitter

The transmitter takes the serial input transmit data from the base-band. This data is GFSK modulated to I and

Q signals. The Tx bit clock is provided to the base-band for synchronization.

The output of the digital part is converted to analogue signals which are lowpass filtered before being sent to

direct up-conversion mixers.

The quadrature up-conversion mixers use the same LO as the receiver. 0dBm output power at the antenna port

is achieved with an internal PA, which has 75

Ω balanced RF output. Optional power control is available.

PLL

The on-chip VCO is part of a PLL, the frequency is programmed for the RF channels by the digital part. The tank

resonator circuitry for the VCO is completely integrated.

Process variations on the VCO center frequency are calibrated out automatically. Also the RC time constants

for the analogue lowpass filters are automatically calibrated on chip.

Base-band interface

Unidirectional BlueRF compatible interface is used to control all functions of radio transceiver.

The unidirectional RXMODE2 is supported. STLC2150 has also the capability to provide the recovered clock

and the aligned data to the base-band (Rxmode2+). 4 wires serial JTAG interface is used to access the internal

registers. Also JTAG is used to set channel number and read RSSI.

Crystal oscillator

The STLC2150 has a crystal oscillator to generate 13 MHz reference clock for internal use and for the base-

band chip.

Also a 3.2 or 32 kHz clock for low power modes operation can be provided.