原创 sallen-key design APPNOTE

在RF 解码电路设计中，电路中肯定引用SALLEN-KEY 电路，该电路对于RF 灵敏度具有较大影响。

对此介绍相关SALLEN-KEY 的资料.

https://www.national.com/an/OA/OA-21.pdf

http://webench.national.com/filters/Choose.do

2.MAX7042 SALLEN-KEY 应用

data slicer

The purpose of a data slicer is to take the analog output
of a data filter and convert it to a digital signal. This is
achieved by using a comparator and comparing the ana-
log input to a threshold voltage. The threshold voltage is
set by the voltage on the DS- pin, which is connected to
the negative input of the data-slicer comparator. The pos-
itive input of the data-slicer comparator is connected to
the output of the data filter internally.

Numerous configurations can be used to generate the
data-slicer threshold. For example, the circuit in Figure 3
shows a simple method using only one resistor and one
capacitor. This configuration averages the analog out-
put of the filter and sets the threshold to approximately
50% of that amplitude. With this configuration, the
threshold automatically adjusts as the analog signal
varies, minimizing the possibility for errors in the digital
data. The values of R and C affect how fast the thresh-
old tracks the analog amplitude. Be sure to keep the
corner frequency of the RC circuit much lower than the
lowest expected data rate.
With this configuration, a long string of zeros or ones
can cause the threshold to drift. This configuration
works best if a coding scheme, such as Manchester
coding, which has an equal number of zeros and ones,
is used.
.