Hardware Reference
In-Depth Information
R
5
ʱ
1
ʱ
3
ʲ
3
¼
R
4
;
for the circuit of Fig
:
7
:
22b
ð
7
:
46
Þ
From the above expressions it can be seen that various active and passive sensitiv-
ities of these circuits would be very low and that the non-ideal, non-unity gains of
the CCs may not result in larger errors between the theoretical and experimental
frequencies. This has indeed been substantiated by the experimental results of these
circuits by using AD844 to implement CCII+ s.
Concluding Remarks
In this chapter we have presented a variety of variable frequency oscillators
with particular emphasis on the so-called SRCOs offering a variety of fea-
tures such as employment of grounded capacitors, employment of all
grounded passive elements, availability of explicit current output, fully
un-coupled tuning laws for CO and FO or structures offering least possible
effect of the CC parasitic impedances on the high frequency performance of
the oscillators etc. Quadrature and multiphase oscillator circuits have also
been included which find numerous applications in telecommunication and
measuring systems.
From a much larger variety and number of circuits available in the vast
literature on this topic we have attempted to include only those which, in our
opinion, are better than those omitted from inclusion. Besides this, a major
factor in selecting the circuits has been that all of them use only the basic
types of current conveyors and therefore, can be readily implemented prac-
tically using AD844 CCII+ elements or CCs constructed from IC op-amps
like
A741/ LF356 type op-amps and CA3096 type mixed transistor arrays or
OPA660/OPA860 (which could be easily used as CCs).
It is expected that the catalogue of SRCO circuits provided here serves as a
good source for circuit designers to choose an appropriate circuit for specific
application. Of course, readers interested in knowing more can look into other
alternatives through the references provided at the end of this chapter and
additional references given in the Appendix, at the end of this monograph.
ʼ
References
1. Nandi R (1977) Wien bridge oscillators using current conveyors. Proc IEEE 65:1608-1609
2. Nandi R (1977) New RC oscillators using current conveyors. Int J Electron 42:309-311
3. Soliman AM (1978) A novel variable frequency sinusoidal oscillator using a single current
conveyor. Proc IEEE 66:800
4. Soliman AM (1978) Realization of frequency dependent negative resistance circuits using two
capacitors and a single current conveyor. Proc IEE 125:1336-1337
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