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參數(shù)資料
| 型號(hào)： | RF2516 |
| 廠商： | RF MICRO DEVICES INC |
| 元件分類： | 通信及網(wǎng)絡(luò) |
| 英文描述： | VHF/UHF TRANSMITTER |
| 中文描述： | SPECIALTY TELECOM CIRCUIT, PDSO16 |
| 封裝： | ROHS COMPLIANT, PLASTIC, SSOP-16 |
| 文件頁數(shù)： | 6/20頁 |
| 文件大小： | 295K |
| 代理商： | RF2516 |
Preliminary
11-40
RF2516
Rev A10 010613
11
T
the reset on each flip-flop. The outputs of the flip-flops
are also connected to the charge pump. Each flip-flop
output signal is a series of pulses whose frequency is
related to the flip-flop input frequency.
When both inputs of the flip-flops are identical, the sig-
nals are both frequency- and phase-locked. If they are
different, they will provide signals to the charge pump
which will either charge or discharge the loop filter, or
enter into a high impedance state. The name “tri-state
comparator” comes from this.
The main benefit of this type of detector is the ability to
correct for errors in both phase and frequency. When
locked, the detector uses phase error for correction.
When unlocked, it uses frequency error for correction.
This type of detector will lock under all conditions.
The
charge pump
consists of two transistors, one for
charging the loop filter and the other for discharging
the loop filter. Its inputs are the outputs of the phase
detector flip-flops. Since there are two flip-flops, there
are four possible states. If both amplifier inputs are low,
then the amplifier pair goes into a high impedance
state, maintaining the charge on the loop filter. The
state where both inputs are high will not occur. The
other states are either charging or discharging the loop
filter. The loop filter integrates the pulses coming from
the charge pump to create a control voltage for the
voltage controlled oscillator.
The
VCO
is a tuned differential amplifier with the bases
and collectors cross-coupled to provide positive feed-
back and a 360° phase shift. The tuned circuit is
located in the collectors, and is comprised of internal
varactors and external inductors. The designer selects
the inductors for the desired frequency of operation.
These inductors also provide DC bias for the VCO.
The output of the VCO is buffered and applied to the
prescaler circuit, where it is divided by either 32 or 64,
as selected by the designer, and compared to the ref-
erence oscillator frequency.
The
transmit amplifier
is a two-stage amplifier con-
sisting of a driver and an open collector final stage. It is
capable of providing 10dBm of output power into a
50
load while operating from a 3.6V power supply.
The
lock-detect circuitry
connects to the output of the
phase detector circuitry and is used to disable the
transmitter when the VCO is not phase-locked to the
reference
oscillator.
This
unwanted out-of-band transmission and to provide
compliance with regulatory limits during an unlocked
condition.
is
necessary
to
avoid
There are many possible reasons for the PLL not to be
locked. For instance, there is a short period during the
start of any VCO in which the VCO begins oscillating
and the reference oscillator builds up to full amplitude.
During this period, the frequency will likely be outside
the authorized band. Typically, the VCO starts much
faster than the reference oscillator. Once both VCO
and reference oscillators are running, the phase detec-
tor can start slewing the VCO to the correct frequency,
slowly sliding across 200MHz of occupied spectrum. In
competitive devices, the VCO radiates at full power
under all of these conditions.
The lock protection circuit in the RF2516 is intended to
stabilize quickly after power is applied to the chip, and
to disable the base drive to the transmit amplifier. This
attenuates the output to levels that will be generally
acceptable to regulatory boards as spurious emis-
sions. Once the phase detector has locked the oscilla-
tors, then the lock circuit enables the MOD IN pin for
transmission of the desired data. There is no need for
an external microprocessor to monitor the lock status,
although that can be done with a low current A/D con-
verter in a system micro, if needed. The lock-detect cir-
cuitry contains an internal resistor which, combined
with a designer-chosen capacitor for a particular RC
time constant, filters the lock-detect signal. This signal
is then passed through an internal Schmitt trigger and
used to enable or disable the transmit amplifier.
If the oscillator unlocks, even momentarily, the protec-
tion circuit quickly disables the output until the lock is
stable. These unlocks can be caused by low battery
voltage, poor power supply regulation, severe shock of
the crystal or VCO, antenna loading, component fail-
ure, or a myriad of unexpected single-point failures.
The RF2516 contains onboard band gap reference
voltage circuitry which provides a stable
DC bias
over
varying temperature and supply voltages. Additionally,
the device features a power-down mode, eliminating
battery disconnect switches.
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| RF2516_06 | 制造商:RFMD 制造商全稱:RF Micro Devices 功能描述:VHF/UHF TRANSMIITER |
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| RF2516PCBA-410 | 制造商:RFMD 制造商全稱:RF Micro Devices 功能描述:VHF/UHF TRANSMIITER |
| RF2516TR7 | 制造商:RF Micro Devices Inc 功能描述:IC TXRX 500MHZ QSOP-16 |
| RF2524-000 | 功能描述:TVS DIODE 5V 4CH UNI SMD RoHS:是 類別:過電壓，電流，溫度裝置 >> TVS - 二極管 系列:- 產(chǎn)品培訓(xùn)模塊:Transient Voltage Suppression (TVS) Diodes 產(chǎn)品目錄繪圖:5KP Series Axial Side 標(biāo)準(zhǔn)包裝:1 系列:5KP 電壓 - 反向隔離（標(biāo)準(zhǔn)值）:170V 電壓 - 擊穿:189V 功率（瓦特）:5000W 電極標(biāo)記:雙向 安裝類型:通孔 封裝/外殼:P600，軸向 供應(yīng)商設(shè)備封裝:P600 包裝:剪切帶 (CT) 產(chǎn)品目錄頁面:2371 (CN2011-ZH PDF) 其它名稱:5KP170CACT5KP170CACT-ND5KP170CALFCTF3388CTF3388CT-ND |
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