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KH563 参数 Datasheet PDF下载

KH563图片预览
型号: KH563
PDF下载: 下载PDF文件 查看货源
内容描述: 宽带,低失真驱动器放大器 [Wideband, Low Distortion Driver Amplifier]
分类和应用: 驱动器放大器
文件页数/大小: 13 页 / 261 K
品牌: CADEKA [ CADEKA MICROCIRCUITS LLC. ]
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KH563  
DATA SHEET  
part, relatively constant performance over supply voltage  
is achieved. A current sense in the error current leg of  
the 10X current mirror feeds back to the bias current  
setup providing a current shutdown feature when the  
output current approaches 250mA.  
Get both V and I into terms of just the error current, i ,  
o o err  
using:  
V = i R and  
err  
i
V
R
R
R
i
+VCC  
i = i  
+
= i  
err  
1+  
f
err  
4
g
g
Current Limit  
Ibias  
R
R
i
10X Current Mirror  
V = V + i R = i  
R +R 1+  
o
f
f
err  
i
f
g
Io  
5pF  
Q3  
ierr  
R
R
19  
f
V = i R +R 1+  
Q1  
Q2  
Cx  
Ro  
23  
o
err  
f
i
-VCC  
+VCC  
g   
Vi  
8
Vo  
Rf  
Rg  
and  
Q4  
5pF  
R
R
i
Io  
I = Gi + i = i  
G +1+  
o
err  
f
err  
g   
Ibias  
10X Current Mirror  
Current Limit  
then  
21  
R
R
f
R +R 1+  
-VCC  
f
i
V
g
o
R ≡  
=
o
R
I
i
o
Figure 2: Simplified Circuit Diagram  
Developing the Performance Equations  
G +1+  
R
g
R
f
The KH563 is intended to provide both a controllable  
voltage gain from input to output as well as a controllable  
output impedance. It is best to treat these two operations  
separately with no load in place. Then, with the no-load  
gain and output impedance determined, the gain to the  
load will simply be the no-load gain attenuated by the  
voltage divider formed by the load and the equivalent  
output impedance.  
note that R  
=
o
G +1  
R = 0  
i
Figure 3: Output Impedance Derivation  
Note that the R expression simplifies considerably if  
o
R = 0. Also note that if the forward current gain were to  
i
go to infinity, the output impedance would go to 0. This  
would be the normal op amp topology with a very high  
Figure 3 steps through the output impedance develop-  
ment using an equivalent model of Figure 2. Offering an  
equivalent, non-zero, output impedance into a matched  
load allows the KH563 to operate at lower internal volt-  
age swings for a given desired swing at the load. This  
allows higher voltage swings to be delivered at the load  
for a given power supply voltage at lower distortion levels  
than an equivalent op amp needing to generate twice the  
voltage swing actually desired at the matched load. This  
improved distortion is specified and tested over a wide  
range as shown in the specification listing.  
internal gain. The KH563 achieves a non-zero R by  
o
setting the internal forward gain to be a low, well  
controlled, value.  
Developing the No-Load Gain Expression  
Taking the output impedance expression as one con-  
straint setting the external resistor values, we now need  
to develop the no-load voltage gain expression from the  
non-inverting input to the output as the other constraint.  
Figure 4 shows the derivation of the no load gain.  
+
+
V
i
X1  
X1  
R
o
V
V
o
o
R
R
i
i
-
l
-
o
Gi  
Gi  
err  
err  
i
i
err  
err  
-
-
V
i
f
V
R
f
R
f
R
R
g
g
REV. 1A January 2008  
7