– –
– –
10
11
1. 2.00V/div
2. 2.00V/div
1ms/div
1
2
BAUDx
READY
3.9ms
1. 2.00V/div
2. 2.00V/div
500µs/div
1
2
CHN_SELx
READY
0.53ms
1. 2.00V/div
2. 2.00V/div
500µs/div
1
2
T/R_SEL
READY
680µs
Module Description
The NT Series transceiver (Figure 20) is a low-cost, high-performance
synthesized FSK transceiver capable of transmitting and receiving serial
data at up to 300kbps. Its exceptional sensitivity results in outstanding
range performance. The module’s compact surface-mount package is
friendly to automated or hand production. NT Series modules are capable
of meeting the regulatory requirements of many domestic and international
applications.
RSSI/
LOGAMP
LNA
FSK
DEMOD
CDR
AFC
AGC
PROCESSOR
26MHz
OSC
PA RAMP
PROFILE
PA
8-BIT
ADC
LOOP
FILTER
CHARGE
PUMP
PFD
DIVIDER
Σ-Δ
MODULATOR
GAUSSIAN
FILTER
f
DEV
DIVIDER
LNA
ANTENNA
GPIO /
INTERFACE
LDO
VCC
PDN
INTERFACE /
VOLTAGE
TRANSLATION
Theory of Operation
The NT Series transceiver is a highly integrated FSK transceiver designed
for operation in the 863–870MHz and 902–928MHz frequency bands.
The RF synthesizer contains a VCO and a low-noise fractional-N PLL. The
VCO operates at two times the fundamental frequency to reduce spurious
emissions. The receive and transmit synthesizers are integrated, enabling
them to be automatically configured to achieve optimum phase noise,
modulation quality and settling time.
The transmitter output power is programmable from −15.5dBm to
+12.5dBm with automatic PA ramping to meet transient spurious
specifications. The ramping and frequency deviation are optimized in each
of four baud bands to deliver the highest performance over a wide range of
data rates.
The receiver incorporates highly efficient low-noise amplifiers that provide
up to −113dBm sensitivity. All of the filters are optimized to the highest
performance in each of the four baud bands. Advanced interference
blocking makes the transceiver extremely robust when in the presence of
interferers.
Figure 17: NT Series Transceiver RX to TX Change Time
Figure 18: NT Series Transceiver Channel Change Time
Figure 19: NT Series Transceiver Baud Band Change Time
Figure 20: NT Series Transceiver Block Diagram
