Hardware Reference
In-Depth Information
Fig. 11.2 The symbolic
notation of the FTFN and its
transmission matrix
i
1
i
2
3
1
+
+
V
1
V
2
-
-
2
4
0
v
1
0
0
v
2
=
i
1
0
0
−
i
2
implementation of the FTFN have been introduced by Nordholt [
6
] Stevenson [
7
]
and Senani [
8
] using commercially available Op-amps [
7
], using BJTs [
4
,
5
]or
using combination of an op-amp, an OTA and a few resistors [
8
]. However, a
particular implementation of the FTFN which can be obtained by a composite
connection of two CCIIs, first suggested by Senani in [
8
], has been particularly
popular and has been employed by numerous researchers in verifying FTFN-based
circuits. This implementation is based upon the identification that a CCII
is a
three terminal nullor hence using the nullor identity shown in Fig.
11.2
; two CCII
can be appropriately connected to constitute an FTFN. Incidentally, if CCII
are
replaced by CCII+, the modified circuit still implements an FTFN and is now
realizable with two AD844 ICs (see Fig.
11.2
).
FTFN has been recognized in the literature as an universal building block and
has been extensively used in the realization of universal filter, SRCOs, synthetic
impedances, inverse filters and numerous others applications. However, the most
significant application of the FTFNs has been in the areas of floating impedance
simulation and generating equivalents of op-amp-RC sinusoidal oscillator config-
urations [
9
-
20
] (Fig.
11.3
).
¼
v
2
v
1
i
1
00
00
i
2
An exhaustive bibliography on FTFNs and their applications in analog circuit
analysis, synthesis and design has been presented in [
21
] whereas a concise
treatment of major developments taken place in this area has been presented in
Chap.
2
of the topic [
22
].
Search WWH ::
Custom Search