JN517X Datasheet, PDF (26/100 Pages) NXP Semiconductors – Supports multiple network stacks

NXP Semiconductors
JN517x
IEEE802.15.4 Wireless Microcontroller
LNA
SWITCH
PA
RADIO
LIM1 LIM2 LIM3 LIM4
D-TYPE
CALIBRATION
REFERENCE
AND BIAS
ADC
SYNTH
SIGMA
DELTA
aaa-023992
Fig 15. Radio architecture
The radio comprises a low-IF receive path and a direct modulation transmit path, which
converge at the TX/RX switch. The switch connects to the external single ended matching
network, which consists of two inductors and a capacitor; this arrangement creates a 50 
port and removes the need for a balun. A 50  single-ended antenna can be connected
directly to this port.
The 32 MHz crystal oscillator feeds a divider, which provides the frequency synthesizer
with a reference frequency. The synthesizer contains programmable feedback dividers,
phase detector, charge pump and internal Voltage Controlled Oscillator (VCO). The VCO
has no external components, and includes calibration circuitry to compensate for
differences in internal component values due to process and temperature variations. The
VCO is controlled by a Phase-Locked Loop (PLL) that has an internal loop filter. A
programmable charge pump is also used to tune the loop characteristic.
The receiver chain starts with the low noise amplifier/mixer combination whose outputs
are passed to a low pass filter, which provides the channel definition. The signal is then
passed to a series of amplifier blocks forming a limiting strip. The signal is converted to a
digital signal before being passed to the Modem. The gain control for the RX path is
derived in the Automatic Gain Control (AGC) block within the Modem, which samples the
signal level at various points down the RX chain. To improve the performance and reduce
current consumption, automatic calibration is applied to various blocks in the RX path.
In the transmit direction, the digital stream from the Modem is passed to a digital
sigma-delta modulator which controls the feedback dividers in the synthesizer (dual point
modulation). The VCO frequency now tracks the applied modulation. The 2.4 GHz signal
from the VCO is then passed to the RF Power Amplifier (PA), whose power control can be
selected from one of three settings. The output of the PA drives the antenna via the RX/TX
switch
JN517X
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2.0 — 8 November 2016
© NXP Semiconductors N.V. 2016. All rights reserved.
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