关于压控电流放大器的问题# EE - 电子工程
i*c
1 楼
Look for nanny to take care 8-month boy near Shady Grove Hospital area.
Either live-in or dropoff at around-area is okay.
Either live-in or dropoff at around-area is okay.
s*e
2 楼
需要设计一个由弱电压来控制强输出电流的电路
输入电压大概模5v，低频；输出电流要求最高能达到500mA
我找了场效应管，因为它是电压控制电流型，可是场效应管的增益太低了，我找到输出
最大振幅的只有100mA的管子。
想问问大家还有什么建议，是不是简单的一级放大电路没法实现呢？
输入电压大概模5v，低频；输出电流要求最高能达到500mA
我找了场效应管，因为它是电压控制电流型，可是场效应管的增益太低了，我找到输出
最大振幅的只有100mA的管子。
想问问大家还有什么建议，是不是简单的一级放大电路没法实现呢？
a*s
3 楼
一级怕是不顶. 怎么也要个运放+反馈电路吧
【在 s******e 的大作中提到】
: 需要设计一个由弱电压来控制强输出电流的电路
: 输入电压大概模5v，低频；输出电流要求最高能达到500mA
: 我找了场效应管，因为它是电压控制电流型，可是场效应管的增益太低了，我找到输出
: 最大振幅的只有100mA的管子。
: 想问问大家还有什么建议，是不是简单的一级放大电路没法实现呢？
【在 s******e 的大作中提到】
: 需要设计一个由弱电压来控制强输出电流的电路
: 输入电压大概模5v，低频；输出电流要求最高能达到500mA
: 我找了场效应管，因为它是电压控制电流型，可是场效应管的增益太低了，我找到输出
: 最大振幅的只有100mA的管子。
: 想问问大家还有什么建议，是不是简单的一级放大电路没法实现呢？
f*0
4 楼
you have two issues to solve, both are very easy.
a) use an opamp where you pick up the feedback via a current sampling
resistor in the same loop with the load. vs. the traditional topology, you
need just one more resistor.
b) find a high current output opamp. I would look into high speed dsl
drivers. ad815 (preferred in a sip package, not soic), tpa6120/ths6012, etc.
most of those adsl drivers are duo opamps with high slew rates and high
current capabilities.
now, if that's difficult for you (t
a) use an opamp where you pick up the feedback via a current sampling
resistor in the same loop with the load. vs. the traditional topology, you
need just one more resistor.
b) find a high current output opamp. I would look into high speed dsl
drivers. ad815 (preferred in a sip package, not soic), tpa6120/ths6012, etc.
most of those adsl drivers are duo opamps with high slew rates and high
current capabilities.
now, if that's difficult for you (t
f*0
5 楼
"是不是简单的一级放大电路没法实现呢？"
sure. just put a bjt in front of it and you can easily control the gain.
sure. just put a bjt in front of it and you can easily control the gain.
s*e
6 楼
that's good. thank you so much!
you can send the schematics to my mail box: w******[email protected]
you can send the schematics to my mail box: w******[email protected]
s*e
7 楼
that's good. thank you so much!
you can send the schematics to my mail box: w******[email protected]
you can send the schematics to my mail box: w******[email protected]
f*0
8 楼
on further reflection, I think it is much easier for you to use one of those
audio power IC (tda2030, tda2003, lm1875, etc.). they are usually in a
to220-5 package, and you need a few resistors to get it to work. they are
10w power amps into 8ohm so it shouldn't be difficult to drive 500ma (unless
your load is super tough).
audio power IC (tda2030, tda2003, lm1875, etc.). they are usually in a
to220-5 package, and you need a few resistors to get it to work. they are
10w power amps into 8ohm so it shouldn't be difficult to drive 500ma (unless
your load is super tough).
f*0
9 楼
here is how "current feedback" works.
R1 is your load, R2 is the sampling resistor that converts the current going
through R1, I1, into a voltage signal to be fed back the inverting end of
the opamp through R6/R3.
so it follows that
I1*R2*R6/(R6+R3)=Vin.
or I1=(1+R3/R6)*Vin/R2.
I typically choose R2 to be < 1/10 of R1, and R3/R6 will depend on what
opamps you use and what input impedance you need.
if you use a regular voltage feedback opamp, I would chose R3=10k.
if no DC blocking capacitor is u
R1 is your load, R2 is the sampling resistor that converts the current going
through R1, I1, into a voltage signal to be fed back the inverting end of
the opamp through R6/R3.
so it follows that
I1*R2*R6/(R6+R3)=Vin.
or I1=(1+R3/R6)*Vin/R2.
I typically choose R2 to be < 1/10 of R1, and R3/R6 will depend on what
opamps you use and what input impedance you need.
if you use a regular voltage feedback opamp, I would chose R3=10k.
if no DC blocking capacitor is u
s*e
10 楼
that's good. thank you so much!
you can send the schematics to my mail box: w******[email protected]
you can send the schematics to my mail box: w******[email protected]
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