RFB433B Micrel Inc, RFB433B Datasheet - Page 3

• Manufacturer Part Number: RFB433B
• Manufacturer: Micrel Inc

Specifications of RFB433B

• Operating Frequency (max): 434000kHz
• Operating Temperature (min): -20C
• Operating Temperature Classification: Commercial
• Modulation Type: FSK
• Operating Supply Voltage (typ): 3V
• Lead Free Status / Rohs Status: Not Compliant

Name
GND
RSSI
LD
GND
XOSCIN
DIGVDD
PUEXT
DATA
General Description
The transmitter section consists of a PLL frequency
synthesizer and a power amplifier. The frequency
synthesizer consists of a voltage-controlled oscillator
(VCO), a crystal oscillator, dual modulus prescaler,
programmable frequency dividers and a phase-detector.
The VCO is a Colpitts oscillator with internal resonator
and varactor. FSK modulation is applied to the VCO. The
output power of the power amplifier can be programmed
to 8 levels. A lock-detect circuit detects when the PLL is
in lock.
In receive mode the PLL synthesizer generates the local
oscillator (LO) signal. The N, M and A values that give
the LO frequency are stored in the N0, M0 and A0
registers. The receiver is a zero intermediate frequency
(IF) type in order to make channel filtering possible with
low power integrated low-pass filters. The receiver
consists of a low noise amplifier (LNA) that drives a
quadrature mixer pair. The mixer outputs feed two
identical signal channels in phase quadrature. Each
channel include a pre-amplifier, a third order Sallen-Key
RC lowpass filter that protects the following gyrator filter
Pin Configuration
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Description
Ground plane connection
Analog received signal strength indicator
output (optional use)
Lock detect output (optional use)
Ground plane connection
Crystal oscillator input (optional use)
Digital circuitry power
External power down (0=power down)
Bi directional RX / TX data
Name
CLK
REG
GND
RF I/O
RFVDD
GND
PIN
IFVDD
from strong adjacent channel signals and finally a limiter.
The main channel filter is a gyrator-capacitor
implementation of a seven-pole elliptic lowpass filter. The
elliptic filter minimizes the total capacitance required for a
given selectivity and dynamic range. The cut-off
frequency of the Sallen-Key RC filter can be
programmed to four different frequencies: 10kHz, 30kHz,
60kHz and 200kHz. Due to the tolerance of the internal
x-tal and selected deviation this filter should be set to
60kHz. The demodulator demodulates the I and Q
channel outputs and produces a digital data output. It
detects the relative phase of the I and the Q channel
signal. If t h e I channel signal lags the Q channel, the
FSK tone frequency lies above the LO frequency (data
‘1’). If the I channel leads the Q channel, the FSK tone
lies below the LO frequency (data ‘0’). The output of the
receiver is available on the DATA pin. A RSSI circuit
(receive signal strength indicator) indicates the received
signal level. A T/R switch is implemented with 2 pin
diodes to give maximum input sensitivity and output
power.
A two pin serial interface is used to program the module.
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Description
Control register data clock
Control register data input, programming of RF
block
Ground plane connection
50
LNA and PA power
Ground plane connection
TX/RX switch control input
IF power
RF input / output
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