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参数资料
| 型号： | LT1228MJ8#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 1 CHANNEL, VIDEO AMPLIFIER, CDIP8 |
| 封装： | 0.300 INCH, HERMETIC SEALED, LEAD FREE, CERAMIC, DIP-8 |
| 文件页数： | 8/20页 |
| 文件大小： | 401K |
| 代理商： | LT1228MJ8#TRPBF |
16
LT1228
1228fc
Single Supply Wien Bridge Oscillator
LT1228 TA14
–
+
–
+
gm
CFA
VO
8
3
2
5
RF
680
RG
20
4
1
6
V+
7
10k
10k
1.8k
160
1000pF
160
+
10
F
+
10
F
V+
470
+
10
F
100
0.1
F
51
50
2N3906
6V TO 30V
f = 1MHz
FOR 5V OPERATION SHORT OUT 100
RESISTOR
VO = 6dBm (450mVRMS)
2nd HARMONIC = –38dBc
3rd HARMONIC = –54 dBc
In this application the LT1228 is biased for operation from
a single supply. An artificial signal ground at half supply
voltage is generated with two 10k resistors and bypassed
with a capacitor. A capacitor is used in series with RG to set
the DC gain of the current feedback amplifier to unity.
The transconductance amplifier is used as a variable
resistor to control gain. A variable resistor is formed by
driving the inverting input and connecting the output back
to it. The equivalent resistor value is the inverse of the gm.
This works with the 1.8k resistor to make a variable
attenuator. The 1MHz oscillation frequency is set by the
Wien bridge network made up of two 1000pF capacitors
and two 160
resistors.
For clean sine wave oscillation, the circuit needs a net gain
of one around the loop. The current feedback amplifier has
a gain of 34 to keep the voltage at the transconductance
amplifier input low. The Wien bridge has an attenuation of
3 at resonance; therefore the attenuation of the 1.8k
resistor and the transconductance amplifier must be about
11, resulting in a set current of about 600
A at oscillation.
At start-up there is no set current and therefore no attenu-
ation for a net gain of about 11 around the loop. As the
output oscillation builds up it turns on the PNP transistor
which generates the set current to regulate the output
voltage.
12MHz Negative Resistance LC Oscillator
LT1228 TA15
–
+
–
+
gm
CFA
VO
8
3
2
1k
330
4
1
6
V+
7
1k
30pF
51
50
VO = 10dB
AT VS = ±5V ALL HARMONICS 40dB DOWN
AT VS = ±12V ALL HARMONICS 50dB DOWN
9.1k
750
V–
5
4.3k
4.7
H
10k
0.1
F
V–
2N3904
2N3906
This oscillator uses the transconductance amplifier as a
negative resistor to cause oscillation. A negative resistor
results when the positive input of the transconductance
amplifier is driven and the output is returned to it. In this
example a voltage divider is used to lower the signal level
at the positive input for less distortion. The negative
resistor will not DC bias correctly unless the output of the
transconductance amplifier drives a very low resistance.
Here it sees an inductor to ground so the gain at DC is zero.
The oscillator needs negative resistance to start and that
is provided by the 4.3k resistor to Pin 5. As the output level
rises it turns on the PNP transistor and in turn the NPN
which steals current from the transconductance amplifier
bias input.
TYPICAL APPLICATIO S
U
相关PDF资料 |
PDF描述 |
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| LT1228MJ8#TR | 1 CHANNEL, VIDEO AMPLIFIER, CDIP8 |
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| LT1304CS8-3.3#TRPBF | 1.2 A SWITCHING REGULATOR, 300 kHz SWITCHING FREQ-MAX, PDSO8 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1229 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual and Quad 100MHz Current Feedback Amplifiers |
| LT1229C | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual and Quad 100MHz Current Feedback Amplifiers |
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| LT1229CN8 | 功能描述:IC CURRNT FEEDBACK AMP DUAL 8DIP RoHS:否 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:73 系列:Over-The-Top® 放大器类型:通用 电路数:4 输出类型:满摆幅 转换速率:0.07 V/µs 增益带宽积:200kHz -3db带宽:- 电流 - 输入偏压:1nA 电压 - 输入偏移:285µV 电流 - 电源:50µA 电流 - 输出 / 通道:25mA 电压 - 电源，单路/双路(±):2 V ~ 44 V，±1 V ~ 22 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:16-WFDFN 裸露焊盘 供应商设备封装:16-DFN-EP（5x3） 包装:管件 |
| LT1229CN8#PBF | 功能描述:IC CURRNT FEEDBACK AMP DUAL 8DIP RoHS:是 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:2,500 系列:- 放大器类型:通用 电路数:4 输出类型:- 转换速率:0.6 V/µs 增益带宽积:1MHz -3db带宽:- 电流 - 输入偏压:45nA 电压 - 输入偏移:2000µV 电流 - 电源:1.4mA 电流 - 输出 / 通道:40mA 电压 - 电源，单路/双路(±):3 V ~ 32 V，±1.5 V ~ 16 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:14-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:14-TSSOP 包装:带卷 (TR) 其它名称:LM324ADTBR2G-NDLM324ADTBR2GOSTR |
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