SX1233 Ver la hoja de datos (PDF) - Semtech Corporation

Número de pieza

componentes Descripción

Fabricante

SX1233

High Bit Rate Transceiver Low Power Integrated UHF Transceiver

Semtech Corporation 

SX1233

ADVANCED COMMUNICATIONS & SENSING

DATASHEET

3.4.4. OOK Modulation

OOK modulation is applied by switching on and off the Power Amplifier. Digital control and smoothing are available to

improve the transient power response of the OOK transmitter.

3.4.5. Modulation Shaping

Modulation shaping can be applied in both OOK and FSK modulation modes, to improve the narrowband response of the

transmitter. Both shaping features are controlled with PaRamp bits in RegPaRamp.

Š In FSK mode, a Gaussian filter with BT = 0.3, 0.5 or 1 is used to filter the modulation stream, at the input of the sigma-

delta modulator. If the Gaussian filter is enabled when the SX1233 is in Continuous mode, DCLK signal on pin 10

(DIO1/DCLK) will trigger an interrupt on the uC each time a new bit has to be transmitted. Please refer to section 5.4.2

for details.

Š When OOK modulation is used, the PA bias voltages are ramped up and down smoothly when the PA is turned on and

off, to reduce spectral splatter.

Note the transmitter must be restarted if the PaRamp setting is changed, in order to recalibrate the built-in filter.

3.4.6. Power Amplifiers

Three power amplifier blocks are embedded in the SX1233. The first one, herein referred to as PA0, can generate up to

+13 dBm into a 50 Ohm load. PA0 shares a common front-end pin RFIO (pin 21) with the receiver LNA.

PA1 and PA2 are both connected to pin PA_BOOST (pin 23), allowing for two distinct power ranges:

Š A low power mode, where -18 dBm < Pout < 13 dBm, with PA1 enabled

Š A higher power mode, when PA1 and PA2 are combined, providing up to +17 dBm to a matched load.

When PA1 and PA2 are combined to deliver +17 dBm to the antenna, a specific impedance matching / harmonic filtering

design is required to ensure impedance transformation and regulatory compliance.

All PA settings are controlled by RegPaLevel, and the truth table of settings is given in Table 10.

Table 10 Power Amplifier Mode Selection Truth Table

Pa0On Pa1On Pa2On

Mode

Power Range

1

0

0

PA0 output on pin RFIO

-18 to +13 dBm

0

1

0

PA1 enabled on pin PA_BOOST

-18 to +13 dBm

0

1

1

PA1 and PA2 combined on pin PA_BOOST -14 to +17 dBm

Other combinations

Reserved

Pout Formula

-18 dBm + OutputPower

-18 dBm + OutputPower

-14 dBm + OutputPower

Notes - To ensure correct operation at the highest power levels, please make sure to adjust the Over Current Protection

Limit accordingly in RegOcp.

- If PA_BOOST pin is not used (+13dBm applications and less), the pin can be left floating.

Rev 3.April 2010

Page 21

www.semtech.com

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