INTRODUCTION TO VHDL-AMS
103
Figure 6-48. Results of test-bench simulation (digital Bessel lowpass filter)
Further Attributes
Table 6-3 summarizes additional new attributes of VHDL-AMS to
describe analog behavior in detail.
Table 6-3. Further VHDL-AMS attributes
Attribute name
Prefix
Result
N'ACROSS
N is any nature
Across type of the nature denoted
by N
N'THROUGH
N is any nature
Through type of the nature denoted
by N
T'REFERENCE
T is any terminal
Across quantity whose plus
terminal is T and whose minus
terminal is the reference terminal of
the nature of T ("node voltage")
T'CONTRIBUTION
T is any terminal
Contribution quantity of terminal T
T'TOLERANCE
T is any floating point type or
subtype T
String with the tolerance group of T
Q'TOLERANCE
Q is any scalar quantity
denoted by the static name Q
String with the tolerance group of Q
6.3.6
Example higher order lowpass filter
The 'LTF attribute, mentioned in the previous section, provides a very
simple mechanism in VHDL-AMS to describe filter functions using their
coefficients. The transfer functions of lowpass filters are often described as a
product of second order filters
)
1
(
1
)
(
2
S
d
S
c
S
H
i
i
i
where
c
f
s
S
2
Summary :
Further VHDL-AMS attributes Attribute name Prefix Result N'ACROSS N is any nature Across type of the nature denoted by N N'THROUGH N is any nature Through type of the nature denoted by N T'REFERENCE T is any terminal Across quantity whose plus terminal is T and whose minus terminal is the reference terminal of the nature of T ("node voltage") T'CONTRIBUTION T is any terminal Contribution quantity of terminal T T'TOLERANCE T is any floating point type or subtype T String with the tolerance group of T Q'TOLERANCE Q is any scalar quantity denoted by the static name Q String with the tolerance group of Q 6.3.6 Example higher order lowpass filter The 'LTF attribute, mentioned in the previous section, provides a very simple mechanism in VHDL-AMS to describe filter functions using their coefficients.
Tags :
any,terminal,nature,hdlams,filter,quantity,denoted,lowpass,type,attributes,table,order,further