參數(shù)資料
型號(hào)： ADF4154BCP-REEL
廠商： ANALOG DEVICES INC
元件分類(lèi)： XO, clock
英文描述： Fractional-N Frequency Synthesizer
中文描述： PLL FREQUENCY SYNTHESIZER, 4000 MHz, QCC20
封裝： 4 X 4 MM, MO-220VGGD-1, LFCSP-20
文件頁(yè)數(shù)： 17/20頁(yè)
文件大?。?/td> 470K
代理商： ADF4154BCP-REEL
ADF4154
For example, in a GSM 1800 system, where a 1.8 GHz RF
frequency output (RF
OUT
) is required, a 13 MHz reference
frequency input (REF
IN
) is available and a 200 kHz channel
resolution (f
RES
) is required on the RF output.
=
MOD
Rev. 0 | Page 17 of 20
65
kHz
200
MHz
13
=
=
f
REF
MOD
RES
IN
From Equation 4,
F
PFD
= [13 MHz × (1 + 0)/1] = 13 MHz
MHz
13
8
≥
=
FRAC
INT
(5)
30
;
138
65
=
≥
+
×
=
FRAC
INT
G
(6)
MODULUS
The choice of modulus (MOD) depends on the reference signal
(REF
IN
) available and the channel resolution (f
RES
) required at
the RF output. For example, a GSM system with 13 MHz REF
IN
would set the modulus to 65, resulting in the RF output resolu-
tion (f
RES
) of 200 kHz (13 MHz/65) that is necessary for GSM.
REFERENCE DOUBLER AND REFERENCE DIVIDER
The reference doubler on-chip allows the input reference signal
to be doubled. This is useful for increasing the PFD comparison
frequency. Making the PFD frequency higher improves the
noise performance of the system. Doubling the PFD frequency
usually results in an improvement in noise performance of 3 dB.
It is important to note that the PFD cannot be operated above
32 MHz due to a limitation in the speed of the Σ-Δ circuit of
the N divider.
12-BIT PROGRAMMABLE MODULUS
Unlike most other fractional-N PLLs, the ADF4154 allows the
user to program the modulus over a 12-bit range. This means
that the user can set up the part in many different configura-
tions for the application, when combined with the reference
doubler and the 4-bit R counter.
For example, consider an application that requires a 1.75 GHz
RF and a 200 kHz channel step resolution. The system has a
13 MHz reference signal.
One possible setup is feeding the 13 MHz directly to the PFD
and programming the modulus to divide by 65, which would
result in the required 200 kHz resolution.
Another possible setup is using the reference doubler to create
26 MHz from the 13 MHz input signal. The 26 MHz signal is
then fed into the PFD, which programs the modulus to divide
by 130. This setup also results in 200 kHz resolution and offers
superior phase noise performance over the previous setup.
The programmable modulus is also very useful for multi-
standard applications. If a dual-mode phone requires PDC and
GSM 1800 standards, the programmable modulus is a huge
benefit. The PDC requires a 25 kHz channel step resolution,
whereas the GSM 1800 requires a 200 kHz channel step
resolution. A 13 MHz reference signal could be fed directly to
the PFD. The modulus would be programmed to 520 when in
PDC mode (13 MHz/520 = 25 kHz). The modulus would be
reprogrammed to 65 for GSM 1800 operation (13 MHz/65 =
200 kHz). It is important that the PFD frequency remains con-
stant (13 MHz). By keeping the PFD constant, the user can
design a one-loop filter that can be used in both setups without
running into stability issues. The ratio of the RF frequency to
the PFD frequency affects the loop design. Keeping this
relationship constant instead of changing the modulus factor
results in a stable filter.
SPURIOUS OPTIMIZATION AND FAST-LOCK
The ADF4154 can be optimized for low spurious signals by
using the noise and spur register. However, in order to achieve
fast-lock time, a wider loop bandwidth is needed. Note that a
wider loop bandwidth can lead to notable spurious signals,
which cannot be reduced significantly by the loop filter.
Using the fast-lock feature can achieve the same fast-lock time
as the noise and spur register, but with the advantage of lower
spurious signals, since the final loop bandwidth is reduced by
a quarter.
FAST-LOCK TIMER AND REGISTER SEQUENCES
If the fast-lock mode is used, a timer value needs to be loaded
into the PLL to determine the time of the wide bandwidth.
When the load control bit = 1, the timer value is loaded via the
12-bit modulus value. To use fast-lock, the PLL must be written
to in the following sequence:
1.
Load the
R-divider register
with DB23 = 1 and the chosen
fast-lock timer value (DB13–DB2) instead of the modulus.
Note that the duration of time the PLL remains in wide
bandwidth is equal to the fast-lock timer/F
PFD
.
2.
Load the
noise and spur register
.
3.
Load the
control register
.
4.
Load
R-divider register
with DB23 = 0 and MUXOUT =
110 (DB22–DB20). All the other needed parameters,
including the modulus, also need to be loaded.
5.
Load the
N-divider register
,
including fast-lock = 1
(DB23), to activate fast-lock mode.
Once this procedure is completed, future frequency jumps
deploying fast-lock need to repeat only Step 5.
相關(guān)PDF資料
PDF描述
ADF4154BCP-REEL7 Fractional-N Frequency Synthesizer
ADF4154BRU Fractional-N Frequency Synthesizer
ADF4154BRU-REEL Fractional-N Frequency Synthesizer
ADF4154BRU-REEL7 Fractional-N Frequency Synthesizer
ADF4193 Low Phase Noise, Fast Settling PLL Frequency Synthesizer
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADF4154BCP-REEL7 制造商:Analog Devices 功能描述:PLL Frequency Synthesizer Single 20-Pin LFCSP EP T/R
ADF4154BCPZ 功能描述:IC FRACTION-N FREQ SYNTH 20LFCSP RoHS:是 類(lèi)別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 時(shí)鐘發(fā)生器，PLL，頻率合成器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:Precision Edge® 類(lèi)型:時(shí)鐘/頻率合成器 PLL:無(wú) 輸入:CML，PECL 輸出:CML 電路數(shù):1 比率 - 輸入:輸出:2:1 差分 - 輸入:輸出:是/是 頻率 - 最大:10.7GHz 除法器/乘法器:無(wú)/無(wú) 電源電壓:2.375 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:16-VFQFN 裸露焊盤(pán)，16-MLF? 供應(yīng)商設(shè)備封裝:16-MLF?（3x3） 包裝:帶卷 (TR) 其它名稱:SY58052UMGTRSY58052UMGTR-ND
ADF4154BCPZ-RL 功能描述:IC FRACTION-N FREQ SYNTH 20LFCSP RoHS:是 類(lèi)別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 時(shí)鐘發(fā)生器，PLL，頻率合成器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:Precision Edge® 類(lèi)型:時(shí)鐘/頻率合成器 PLL:無(wú) 輸入:CML，PECL 輸出:CML 電路數(shù):1 比率 - 輸入:輸出:2:1 差分 - 輸入:輸出:是/是 頻率 - 最大:10.7GHz 除法器/乘法器:無(wú)/無(wú) 電源電壓:2.375 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:16-VFQFN 裸露焊盤(pán)，16-MLF? 供應(yīng)商設(shè)備封裝:16-MLF?（3x3） 包裝:帶卷 (TR) 其它名稱:SY58052UMGTRSY58052UMGTR-ND
ADF4154BCPZ-RL7 功能描述:IC FRACTION-N FREQ SYNTH 20LFCSP RoHS:是 類(lèi)別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 時(shí)鐘發(fā)生器，PLL，頻率合成器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:Precision Edge® 類(lèi)型:時(shí)鐘/頻率合成器 PLL:無(wú) 輸入:CML，PECL 輸出:CML 電路數(shù):1 比率 - 輸入:輸出:2:1 差分 - 輸入:輸出:是/是 頻率 - 最大:10.7GHz 除法器/乘法器:無(wú)/無(wú) 電源電壓:2.375 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:16-VFQFN 裸露焊盤(pán)，16-MLF? 供應(yīng)商設(shè)備封裝:16-MLF?（3x3） 包裝:帶卷 (TR) 其它名稱:SY58052UMGTRSY58052UMGTR-ND
ADF4154BRU 功能描述:IC FRAC-N FREQ SYNTH 16-TSSOP RoHS:否 類(lèi)別:集成電路 (IC) >> 時(shí)鐘/計(jì)時(shí) - 時(shí)鐘發(fā)生器，PLL，頻率合成器 系列:- 標(biāo)準(zhǔn)包裝:1,000 系列:Precision Edge® 類(lèi)型:時(shí)鐘/頻率合成器 PLL:無(wú) 輸入:CML，PECL 輸出:CML 電路數(shù):1 比率 - 輸入:輸出:2:1 差分 - 輸入:輸出:是/是 頻率 - 最大:10.7GHz 除法器/乘法器:無(wú)/無(wú) 電源電壓:2.375 V ~ 3.6 V 工作溫度:-40°C ~ 85°C 安裝類(lèi)型:表面貼裝 封裝/外殼:16-VFQFN 裸露焊盤(pán)，16-MLF? 供應(yīng)商設(shè)備封裝:16-MLF?（3x3） 包裝:帶卷 (TR) 其它名稱:SY58052UMGTRSY58052UMGTR-ND
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