參數(shù)資料
型號(hào)： LMX9830
廠商： National Semiconductor Corporation
英文描述： BluetoothTM Serial Port Module
中文描述： 藍(lán)牙串口模塊
文件頁(yè)數(shù)： 21/46頁(yè)
文件大?。?/td> 664K
代理商： LMX9830
21
www.national.com
L
9.0 Digital Smart Radio
(Continued)
The post-detection filter also helps for attenuating the first
adjacent channel signal. The equalizer improves the eye-
opening for 101010 patterns. The post-detection filter is a
third order Butterworth filter.
9.4 AUTOTUNING CIRCUITRY
The autotuning circuitry is used for tuning the bandpass fil-
ter, the detector, the post-detection filter, the equalizer, and
the transmit filters for process and temperature variations.
The circuit also includes an offset compensation for the FM
detector.
9.5 SYNTHESIZER
The synthesizer consists of a phase-frequency detector, a
charge pump, a low-pass loop filter, a programmable fre-
quency divider, a voltage-controlled oscillator (VCO), a del-
ta-sigma modulator, and a lookup table.
The frequency divider consists of a divide-by-2 circuit (di-
vides the 5 GHz signal from the VCO down to 2.5 GHz), a
divide-by-8-or-9 divider, and a digital modulus control. The
delta-sigma modulator controls the division ratio and also
generates an input channel value to the lookup table.
9.5.1 Phase-Frequency Detector
The phase-frequency detector is a 5-state phase-detector.
It responds only to transitions, hence phase-error is inde-
pendent of input waveform duty cycle or amplitude varia-
tions. Loop lockup occurs when all the negative transitions
on the inputs, F_REF and F_MOD, coincide. Both outputs
(i.e., Up and Down) then remain high. This is equal to the
zero error mode. The phase-frequency detector input fre-
quency range operates at 12MHz.
9.6 TRANSMITTER CIRCUITRY
The transmitter consists of ROM tables, two Digital to Ana-
log (DA) converters, two low-pass filters, IQ mixers, and a
power amplifier (PA).
The ROM tables generate a digital IQ signal based on the
transmit data. The output of the ROM tables is inserted into
IQ-DA converters and filtered through two low-pass filters.
The two signal components are mixed up to 2.5 GHz by the
TX mixers and added together before being inserted into
the transmit PA.
9.6.1 IQ-DA Converters and TX Mixers
The ROM output signals drive an I- and a Q-DA converter.
Two Butterworth low-pass filters filter the DA output signals.
The 6 MHz clock for the DA converters and the logic circuit-
ry around the ROM tables are derived from the autotuner.
The TX mixers mix the balanced I- and Q-signals up to 2.4-
2.5 GHz. The output signals of the I- and Q-mixers are
summed.
9.7 CRYSTAL REQUIREMENTS
The LMX9830 contains a crystal driver circuit. This circuit
operates with an external crystal and capacitors to form an
oscillator. Figure 12 on page 22 shows the recommended
crystal circuit. Table 22 on page 24 specifies system clock
requirements.
The RF local oscillator and internal digital clocks for the
LMX9830 is derived from the reference clock at the CLK+
input. This reference may either come from an external
clock or a dedicated crystal oscillator. The crystal oscillator
connections require an Xtal and two grounded capacitors.
It is also important to consider board and design depen-
dant capacitance in tuning crystal circuit. Equations that
follow allow a close approximation of crystal tuning capaci-
tance required, but actual values on board will vary with
capacitive properties of the board. As a result, there is
some fine tuning of crystal circuit that has to be done that
can not be calculated, must be tuned by testing different
values of load capacitance.
Many different crystals can be used with the LMX9830. Key
requirements from Bluetooth specification is + 20ppm.
Additionally, ESR (Equivalent Series Resistance) must be
carefully considered. LMX9830 can support maximum of
230ohm ESR, but it is recommended to stay <100ohms
ESR for best performance over voltage and temperature.
Reference Figure 17 on page 25 for ESR as part of crystal
circuit for more information.
9.7.1 Crystal
The crystal appears inductive near its resonant frequency.
It forms a resonant circuit with its load capacitors. The res-
onant frequency may be trimmed with the crystal load
capacitance.
1. Load Capacitance
For resonance at the correct frequency, the crystal should
be loaded with its specified load capacitance, which is the
value of capacitance used in conjunction with the crystal
unit. Load capacitance is a parameter specified by the
crystal, typically expressed in pF. The crystal circuit shown
in Figure 13 on page 22 is composed of:
■
C1 (motional capacitance)
■
R1 (motional resistance)
■
L1 (motional inductance)
■
C0 (static or shunt capacitance)
The LMX9830 provides some of the load with internal
capacitors C
int
. The remainder must come from the exter-
nal capacitors and tuning capacitors labeled Ct1 and Ct2
as shown in Figure 12 on page 22. Ct1 and Ct2 should
have the same the value for best noise performance.
The LMX9830 has an additional internal capacitance
C
TUNE
of 2.6pF. Crystal load capacitance (C
L)
is calculated
as the following:
C
L
= C
int
+ C
TUNE
+ Ct1//Ct2
The C
L
above does not include the crystal internal self-
capacitance C
0
as shown in Figure 13 on page 22, so the
total capacitance is:
C
total
= C
L
+ C
0
相關(guān)PDF資料
PDF描述
LMX9830SM BluetoothTM Serial Port Module
LMX9830SMX BluetoothTM Serial Port Module
LMX9838 Bluetooth Serial Port Module
LMX9838SB Bluetooth Serial Port Module
LMX9838SBX Bluetooth Serial Port Module
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LMX9830DONGLE 功能描述:藍(lán)牙/802.15.1 開(kāi)發(fā)工具 LMX9830 BLUETOOTH EVAL KIT RoHS:否 制造商:Panasonic Electronic Components 產(chǎn)品:Bluetooth Evaluation Kit 工具用于評(píng)估:PAN1721 頻率:2.4 GHz 接口類(lèi)型:I2C 工作電源電壓:2 V to 3.6 V
LMX9830DONGLE/NOPB 制造商:Texas Instruments 功能描述:Evaluation Kit For Bluetooth Serial Port Module
LMX9830SM 制造商:NSC 制造商全稱:National Semiconductor 功能描述:BluetoothTM Serial Port Module
LMX9830SM/NOPB 功能描述:射頻收發(fā)器 RoHS:否 制造商:Atmel 頻率范圍:2322 MHz to 2527 MHz 最大數(shù)據(jù)速率:2000 Kbps 調(diào)制格式:OQPSK 輸出功率:4 dBm 類(lèi)型: 工作電源電壓:1.8 V to 3.6 V 最大工作溫度:+ 85 C 接口類(lèi)型:SPI 封裝 / 箱體:QFN-32 封裝:Tray
LMX9830SMX 制造商:NSC 制造商全稱:National Semiconductor 功能描述:BluetoothTM Serial Port Module
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