Circuits and Systems, 2013, 4, 264-268
http://dx.doi.org/10.4236/cs.2013.43035 Published Online July 2013 (http://www.scirp.org/journal/cs)
Fully Uncoupled Electronically Controllable Sinusoidal
Oscillator Employing VD-DIBAs
Data Ram Bhaskar1*, Dinesh Prasad1, Kanhaiya Lal Pushkar2
1Department of Electronics and Communication Engineering, Faculty of Engineering and Technology,
Jamia Millia Islamia, New Delhi, India
2Department of Electronics and Communication Engineering, Maharaja Agrasen Institute of Technology, Rohini,
New Delhi, India
Email: *dbhaskar@jmi.ac.in, dprasad@jmi.ac.in, klpushkar@rediffmail.com
Received March 21, 2013; revised April 22, 2013; accepted April 30, 2013
Copyright © 2013 Data Ram Bhaskar et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Recently, voltage differencing-differential input buffered amplifiers (VD-DIBA)-based electronically controllable si-
nusoidal oscillator has been presented that it does not have the capability of complete independence of frequency of
oscillation (FO) and condition of oscillation (CO) as well as electronic control of both CO and FO. In this article, a new
fully-uncoupled electronically controllable sinusoidal oscillator using two VD-DIBAs, two grounded capacitors and two
resistors has been proposed which offers important advantages such as 1) totally uncoupled and electronically con-
trolled condition of oscillation (CO) and frequency of oscillation (FO); 2) low active and passive sensitivities; and 3) a
very good frequency stability factor. The effects of non-idealities of the VD-DIBAs on the proposed oscillator are also
investigated. The validity of the proposed formulation has been confirmed by SPICE simulation with TSMC 0.18 μm
process parameters.
Keywords: Sinusoidal Oscillator; Voltage-Mode; VD-DIBA
1. Introduction
Sinusoidal oscillators find various applications in signal
processing, instrumentation, measurement, communica-
tion and control systems. The class of single resistance
controlled oscillators (SRCOs) using different active
element(s)/device(s) has been of particular interest dur-
ing the last four decades because of their applications in
variable frequency oscillators. However, in these SRCOs,
electronic control of CO and FO can be obtained by re-
placing the respective controlling resistor(s) with FET
based or CMOS voltage controlled resistor(s). A careful
inspection of the available SRCOs reveals that while
many oscillators enjoy independent single element con-
trol of CO and FO, the class of fully uncoupled oscilla-
tors has not been considered adequately in the literature.
In fully uncoupled oscillator circuits CO and FO are de-
termined by two completely different sets of active and/
or passive components, that is none of the active and/or
passive components appeared in CO are involved in FO
and vice versa. This feature is very useful for realizing
voltage controlled oscillators as FO can be controlled
independently without disturbing CO, whereas the flexi-
bility of being able to control CO independently is ad-
vantageous to incorporate amplitude stabilization. In the
recent past, number of fully-uncoupled sinusoidal oscil-
lators employing different active element(s)/devices has
been introduced see [1-7] and the references cited therein.
In references [1-5] the CO and FO of the proposed oscil-
lators are adjustable through resistors (the electronic
tunability can be established by replacing one of the
grounded resistors by JFETs/MOSFETs [8,9]), whereas
in case of oscillators presented in references [6,7], both
CO and FO are electronically controllable. The VD-
DIBA was introduced by Biolek, Senani, Biolkova and
Kolka in [10] since then it has been found to be a useful
new active building block in realizing all voltage-mode
pass filters [11], inductance simulation [12], universal
biquad filter [13] and an electronically controllable sinu-
soidal oscillator [14]. Although the paper presented by
the authors in [14] employs two VD-DIBAs, two grounded
capacitors and one grounded resistor but this circuit does
not have the capability of complete independence of CO
and FO as well as electronic control (only FO is elec-
tronically controllable). Therefore, the purpose of this
*Corresponding author.
C
opyright © 2013 SciRes. CS
D. R. BHASKAR ET AL. 265
paper is, to propose a new fully uncoupled electronically
controllable sinusoidal oscillator employing two VD-
DIBAs, two grounded capacitors and two resistors, which
offers 1) fully uncoupled and electronically controlled
CO and FO, 2) low active and passive sensitivities, and 3)
a very good frequency stability factor. The feasibility of
the proposed oscillator has been demonstrated by SPICE
simulation with TSMC 0.18 μm process parameters.
VD-DIBA(+) VD-DIBA(-)
V
+
V_V
+
V
_Z
ZV V
WW
C2
C1R1
R2
2. The Proposed Fully Uncoupled Oscillator
The schematic symbol and behavioral model of the VD-
DIBA are shown in Figures 1(a) and (b) respectively
[11]. The VD-DIBAs can be described by the following
set of equations:
000
000
000
00
00
00
000
00
110
z
z
vv
w
mm
w
I
V
I
V
I
V
gg
I
V
I

















V








(1)
V0
Figure 2. The proposed fully-uncoupled electronically con-
nd
The proposed new fully-uncoupled electronically con-
trollable sinusoidal oscillator circuit is shown in Figure
2.
Assuming that the VD-DIBAs are characterized by
Equation (1), the characteristic equation (CE) of Figure
2 can be given by:
2
212
0
m
g
RCC

1
2
11
11
m
ss g
CR



 (2)
From this CE, the CO and FO can be found as:
CO
1
1
10
m
g
R




(3)
V+
V_
Iz
v+
v_
Vz
Z
VD-DIB
Iv
Iw
Vv
Vw
V
W
A
(a)
V+
V-
VzVv
Vw
Vz-Vv
Iz
(b)
Figure 1. (a) Schematic symbol; (b) Behavioral model of
trollable sinusoidal oscillator.
a
FO
2
0
212
m
g
RCC
(4)
Therefore, from Equations (3) and (4) it is clear that
FO and CO are fully decoupled and electronically con-
trollable i.e. FO is independently controllable by trans-
conductance 2
m
g
of the VD-DIBA(), whereas CO is
also electroni controllable through the transconduc-
tance 1
m
cally
g
of VD-DIBA(+).
3. Non-Ideal Analysis
f VD-DIBA i.e. RZ and CZ, Considering the parasitics o
the parasitic resistance and the parasitic capacitance of
the Z-terminal respectively. Taking the non-idealities
into account, namely the voltage of W-terminal
W
V


Z
V
VV where

11


pp and
11

nn e voltage trackingrs of
Z-terminal and
denote th erro
V-terminal of the VD-DIBA (+/) re-
spectively, then the expression for CE becomes:
VD-DIBA.



1
2
1
12
2
21
12
22
2
2
21
1
12
21
112
0
z
mz
m
zz
mz
sC g C
RR R
g
CRR
g
RR R
22sC CC










(5)
From Equation (5), the CO and FO can be given by:
CO:



1
2
21
12
22
1
1
1212 0









 
m
z
z
CgC
RR
CC
R
(6)
Copyright © 2013 SciRes. CS
D. R. BHASKAR ET AL.
266
FO:


22
2
22
1
1
1
12
1
2
mmz
z
gg
RRR R
CCC




(7)
ivities of 0
2
The sensit
with respect to active and pas-
sive elements are calculated as:




1
0
1
2
1
2
22
1
2mz
Rg
RR
R R





2
0
2
2
1
0
2
1
0
2
2
1
2
2
2
2
2
2
2
221
2
1
2
2
221
1
112
112
2
1
2
12
112
2
m
m
m
g
m
m
g
mmz
mz
mmz
g
Sg
g
Sg
Rg
RRR R
S
g
RR
Sgg
RRRR

















 










0
1
2
1
0
2
0
2
1
000
12
2
2
2
12
221
2
2
2
2
221
1
112
2
1
2
1
112
1,1
2
z
z
R
mmz
R
R
m
zm
z
CCC
Sg
RR g
RRRR
S
Sg
RR g
RRR R
SSS

 









 








 
(8)
An inspection of Equation (8) reveals that the a
and passive sensitivities of 0
ctive
are found to be low.
4. Frequency Stability
Frequency stability is an important figure of merit for
an F
y sinusoidal oscillator. Using the definition of the fr-
equency stability factor Sas given in [5,8]
F S

1

u
d
d


u
u (where
0
u is the normalized fre-
quency and

u denotes the phase of the open-loop
transfer function), with 1
12
11
, 
m
CCCg
12
m
g
RR
2
mm
ng , the SF of this oscillator is found to
be 2n. Thus the new proposed oscillator circuit offers
very high frequency stability f
oscillator circuit has been simu
lated using the CMOS-based VD-DIBA [14]. The vari-
omponent
7 K
IB7 = 30 μA. The transcon-
ere controlled through the
and
actor for larger values of n.
5. Simulation Results
The proposed sinusoidal-
ous cvalues used were C1 = C2 = 0.05 nF, R1 =
1.6 and R2 = 10 K, the CMOS VD-DIBA was bi-
ased with ±1 V D.C. power supplies with IB1 = IB2 = IB3 =
IB4 = IB5 = IB6 = 150 μA and
ductances of VD-DIBAs w
respective bias currents. The SPICE generated output
waveforms indicating transient and steady state re-
sponses are shown in Figures 3(a) and (b) respectively.
From SPICE simulations {Figures 3(a) and (b)}, the
oscillations are observed to be quite stable and the fre-
quency of generated sine wave was found as 731.88 KHz.
The THD of the output waveform was found as 1.159%.
Figure 4 shows the Monte-Carlo simulations which pro-
vide the robustness of the oscillator circuit of Figure 2
by taking sample result for ±10% variations in R1. Simu-
lation results, thus, confirm the workability of the pro-
g
012
x 10
-4
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
Voltage (V)
Time (S)
(a)
0.1
0.08
0.06
0.04
0.02
0
-0.02
-0.04
-0.06
-0.08
1.5
-0.1 1.51 1.521.53 1.54 1.551.56 1.57 1.58 1.591.6
x 10
-4
Time (S)
Voltage (V)
(b)
Figure 3. (a) Transient output waveform; (b) Steady state
response of the output.
Copyright © 2013 SciRes. CS
D. R. BHASKAR ET AL.
Copyright © 2013 SciRes. CS
267
Time
0s20us40us60us80us100us 120us 140us 160us 180us200us
V(3)
-200mV
0V
200mV
1/ Period(V(3))
720K 724K 728K 732K 736K 740K744K
0
40
%
SEL>>
n samples= 9
n divisions= 10mean= 731819
sigma= 4431.69minimum= 723940
10th %ile= 723940median= 731884
90th %ile= 737724maximum
3*sigma = 737724
= 13295.1
Figure 4. Result of Monte-Carlo simulation of oscillator circuit of Figure 2.
Table 1. Comparison with other previously known fully uncoupled sinusoidal osc illators.
Reference Number No. of Active Elements No. of Passive
Elements
No. of Grounded
Capacitors
Independent Electronic
Tunability in Both CO and FO
[1] 2 6 2 NO
[2] 3 4 - 6 2 - 3 NO
[3] 3 5 2 NO
[4] 1 - 3 3 - 7 2 - 3 NO
[5] 3 6 2 NO
[6] 4 YES
[7] 2 YES
[14] NO
2 2
2 2
2 3 2
Proposed 2 4 2 YES
posed oscillator. A comparison with other previously
known fully uncoupled sinusoidal oscillators has been
given in Table 1.
6. Concluding Remarks
A new siidal oscillator with fully decoupled and
electronically controllable both frequency of oscillation
and condition of oscillation has been presented. The new
oscillator configuration also enjoy1) low active and
passive sensitivities and 2) a very good frequency stabil-
ity factr values of n. Tobustness of the
roposed oscillator circuit has been confirmed by the
Quadrature Sinusoidal Oscillator,” Journal of RF-Engi-
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3-4, 2007, pp.2-104.
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doi:10.1023/A
),
10
[2] llator
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:1008321911123
nuso
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or for largehe r
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