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| 型号： | LTC1068-25CG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 4/30页 |
| 文件大小： | 0K |
| 描述： | IC FILTR BUILDNG BLK QUAD 28SSOP |
| 标准包装： | 47 |
| 滤波器类型： | 通用开关电容器 |
| 频率 - 截止或中心： | 200kHz |
| 滤波器数： | 4 |
| 滤波器阶数： | 8th |
| 电源电压： | 3.14 V ~ 11 V，±3.14 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 管件 |
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LTC1068 Series
12
1068fc
MODES OF OPERATION
Linear Technology’s universal switched-capacitor filters
are designed for a fixed internal, nominal fCLK/fO ratio. The
fCLK/fO ratio is 100 for the LTC1068, 200 for the LTC1068-
200, 50 for the LTC1068-50 and 25 for the LTC1068-25.
Filter designs often require the fCLK/fOratioofeachsection
to be different from the nominal ratio and in most cases
different from each other. Ratios other than the nominal
valuearepossiblewithexternalresistors.Operatingmodes
useexternalresistors,connectedindifferentarrangements
to realize different fCLK/fO ratios. By choosing the proper
mode, the fCLK/fOratiocanbeincreasedordecreasedfrom
the part’s nominal ratio.
The choice of operating mode also effects the transfer
function at the HP/N pins. The LP and BP pins always give
the lowpass and bandpass transfer functions respectively,
regardless of the mode utilized. The HP/N pins have a
different transfer function depending on the mode used.
Mode 1 yields a notch transfer function. Mode 3 yields a
highpasstransferfunction.Mode2yieldsahighpassnotch
transfer function (i.e., a highpass with a stopband notch).
More complex transfer functions, such as lowpass notch,
allpass or complex zeros, are achieved by summing two
or more of the LP, BP or HP/N outputs. This is illustrated
in sections Mode 2n and Mode 3a.
Choosing the proper mode(s) for a particular application
is not trivial and involves much more than just adjusting
the fCLK/fO ratio. Listed here are four of the nearly twenty
modes available. To make the design process simpler and
quicker, Linear Technology has developed the FilterCAD
for Widows design software. FilterCAD is an easy-to-use,
powerful and interactive filter design program. The de-
signer can enter a few filter specifications and the program
produces a full schematic. FilterCAD allows the designer
to concentrate on the filter’s transfer function and not get
bogged down in the details of the design. Alternatively,
those who have experience with the Linear Technology
family of parts can control all of the details themselves.
For a complete listing of all the operating modes, consult
the appendices of the FilterCAD manual or the Help files
in FilterCAD. FilterCAD can be obtained free of charge on
the Linear Technology web site (www.linear.com) or you
can order the FilterCAD CD-ROM by contacting Linear
Technology Marketing.
Mode 1
In Mode 1, the ratio of the external clock frequency to
the center frequency of each 2nd order section is inter-
nally fixed at the part’s nominal ratio. Figure 4 illustrates
Mode 1 providing 2nd order notch, lowpass and band-
pass outputs. Mode 1 can be used to make high order
Butterworth lowpass filters; it can also be used to make
low Q notches and for cascading 2nd order bandpass
functions tuned at the same center frequency. Mode 1 is
faster than Mode 3.
PleaserefertotheOperatingLimitsparagraphunderApplica-
tions Information for a guide to the use of capacitor CC.
Mode 1b
Mode 1b is derived from Mode 1. In Mode 1b (Figure 5)
two additional resistors R5 and R6 are added to lower the
amount of voltage fed back from the lowpass output into
the input of the SA (or SB) switched-capacitor summer.
This allows the filter’s clock-to-center frequency ratio to
be adjusted beyond the part’s nominal ratio. Mode 1b
maintains the speed advantages of Mode 1 and should
be considered an optimum mode for high Q designs with
fCLK to fCUTOFF (or fCENTER) ratios greater than the part’s
nominal ratio.
The parallel combination of R5 and R6 should be kept
below 5k.
PleaserefertotheOperatingLimitsparagraphunderApplica-
tions Information for a guide to the use of capacitor CC.
Figure 4. Mode 1, 2nd Order Filter Providing Notch,
Bandpassing and Lowpass Outputs
–
+
Σ
AGND
R1
N
BP
LP
VIN
1068 F04
+ –
S
R2
R3
CC
fO =
; fn = fO
Q =
; HON = –
; HOBP = –
HOLP = HON
R2
R1
R3
R1
R3
R2
fCLK
RATIO
DEVICE
LTC1068
LTC1068-200
LTC1068-50
LTC1068-25
RATIO
100
200
50
25
相关PDF资料 |
PDF描述 |
|---|---|
| LTC1068-25CG | IC FILTR BUILDNG BLK QUAD 28SSOP |
| LTC1068-200CG | IC FILTR BUILDNG BLK QUAD 28SSOP |
| LTC1569IS8-6#TR | IC FILTER LP 10TH ORD LIN 8SOIC |
| LTC1566-1CS8#TRPBF | IC FILTER LP 7ORDER 2.3MHZ 8SOIC |
| LTC1566-1CS8#TR | IC FILTER LP 7ORDER 2.3MHZ 8SOIC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1068-25IG | 功能描述:IC FILTR BUILDNG BLK QUAD 28SSOP RoHS:否 类别:集成电路 (IC) >> 接口 - 滤波器 - 有源 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1,000 系列:- 滤波器类型:连续时间，带通低通 频率 - 截止或中心:150kHz 滤波器数:4 滤波器阶数:8th 电源电压:4.74 V ~ 11 V，±2.37 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) |
| LTC1068-25IG#PBF | 功能描述:IC FILTR BUILDNG BLK QUAD 28SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 滤波器 - 有源 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1,000 系列:- 滤波器类型:连续时间，带通低通 频率 - 截止或中心:150kHz 滤波器数:4 滤波器阶数:8th 电源电压:4.74 V ~ 11 V，±2.37 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) |
| LTC1068-25IG#TR | 功能描述:IC FILTER BUILDG BLK QUAD 28SSOP RoHS:否 类别:集成电路 (IC) >> 接口 - 滤波器 - 有源 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1,000 系列:- 滤波器类型:连续时间，带通低通 频率 - 截止或中心:150kHz 滤波器数:4 滤波器阶数:8th 电源电压:4.74 V ~ 11 V，±2.37 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) |
| LTC1068-25IG#TRPBF | 功能描述:IC FILTR BUILDNG BLK QUAD 28SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 滤波器 - 有源 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1,000 系列:- 滤波器类型:连续时间，带通低通 频率 - 截止或中心:150kHz 滤波器数:4 滤波器阶数:8th 电源电压:4.74 V ~ 11 V，±2.37 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC W 包装:带卷 (TR) |
| LTC1068-25IG-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Clock-Tunable, Quad Second Order, Filter Building Blocks |
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