This paper examines the performance of a high gain, low noise instrumentation amplifier (INA) utilizing three operational amplifiers tailored for weak biomedical signals, such as ECG. The authors analyze various parameters including gain, bandwidth, output noise, and power dissipation, validating the design using UMC 180nm CMOS technology and Cadence Spectre simulator. Key results demonstrate the amplifier's effective performance in enhancing weak signal detection and processing in biomedical applications.

1. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
33 NITTTR, Chandigarh EDIT-2015
High Gain, Low Noise Instrumentation
Amplifier Using Three Operational Amplifiers
for Weak Biomedical Signal
1
Amit Kumar Chidar, 2
Pramod Kumar Jain, 3
D.S Ajnar
1,2,3
Microelectronics and VLSI Design, E&I Department, S.G.S.I.T.S Indore, M.P, India
1
amitchidar08@gmail.com, 2
prjain@sgsits.ac.in, 3
ajnards@gmail.com
Abstract:- This paper investigate the performance of
Instrumentation amplifier (INA) using three operational
Amplifier. The proposed circuit works for low input voltage
equalised to the heart beat of the human being to analyses the
ECG (Biomedical application) response. The analyses of
Gain, Bandwidth, Unity GBW, Phase margin and output
noise for operational amplifier used in INA and For the INA
Gain, Bandwidth, output noise and power Dissipation are
analysed. The proposed circuit designed on UMC 180nm
CMOS technology file and all the simulation done on
CADENCE SPECTRE Simulator.
Keyword: Amplifier basics, Differential Amplifier using
MOSFET, Operational Amplifier, Instrumentation Amplifier,
ECG (Biomedical application), Analog Electronics.
I. INTRODUCTION
Today Biomedical Application play a vital role in the field
of Technology but, it is very challenging task to fetch the
biomedical signal because of very small amplitude and
frequency of few hertz. As the biomedical signal is very
small and equal to noise if it is difficult task to find it’s
presence. Like Heart Beat signal or Pulse Signal which are
very weak in nature [1, 2]. So, to overcome from this
problem we need proper amplification, modified Gain,
Higher Bandwidth and suppressed noise device like,
Instrumentation Amplifier. An instrumentation amplifier is
the one of the most effective block of Biomedical field
mainly used in some application such as ECG, Transducer
or sensor based biomedical devices, Microelectronics
Devices etc. It provides better amplification, good
linearity, Gain, Bandwidth and having properties of
suppressing noise from the weak biomedical signal.
Basically it constitute of two differential input and single
ended output. The basic building block of biomedical
device is shown below in the Fig.1
Fig. 1 Biomedical Signal Fetching and Detecting Device
The Amplifier used in the device shown above is an
Instrumentation Amplifier working over the Biomedical
signal, the Amplifier shows good CMRR, Gain, BW, Low
power dissipation [3] and Low noise. The Device shown
above with Instrumentation Amplifier provided digital
output pulse after analysing Bio-medical signal. The
Biomedical device such as ECG having quite similar
blocks shown in the Fig. 1 and Instrumentation Amplifier
play an important role in it.
In this paper, SECTION II and SECTION III describe the
operational amplifier and the proposed instrumentation
amplifier respectively. SECTION IV and SECTION V
describe the simulation results and conclusion respectively.
II. DESCRIPTION OF OPERATIONAL AMPLIFIER
FOR DESIGNING OF INA
The basic building block of proposed circuit is an
Operational amplifier. There are three operational
amplifiers used in the proposed INA. Each operational
amplifier is dual stage amplifier basically used to enhance
the gain of the INA. The schematic of operational amplifier
shown below in the Fig. 2.
Fig.2 Operational Amplifier for the Proposed INA
The operational amplifier consist [5] of two stages first
stage is gain stage and second stage is called output stage.
Basically, second stage enhances the gain and provides
frequency compensation through compensation
capacitance Cc. The nmos MOS transistor M1, M2 act as
the differential stage, pmos transistor M3,M4 act as current
mirror, M5, M6 and M8 are used for biasing. The output is
taken out from the output load capacitance, the relationship
between load capacitance CL and compensation
capacitance CC are shown below:-
CL ≥ 2.2Cc........................(1)
Aspect ratio i.e. (W/L ratio) of MOS transistor for the
operational amplifier shown below in the TABLE I:-
TABLE I
Aspect
ratio
M1,
M2
M3,
M4
M5,
M6
M7 M8
W/L
(µm/ µm)
3/.5 7/.5 12/1 87/.5 75/1
Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
33 NITTTR, Chandigarh EDIT-2015
High Gain, Low Noise Instrumentation
Amplifier Using Three Operational Amplifiers
for Weak Biomedical Signal
1
Amit Kumar Chidar, 2
Pramod Kumar Jain, 3
D.S Ajnar
1,2,3
Microelectronics and VLSI Design, E&I Department, S.G.S.I.T.S Indore, M.P, India
1
amitchidar08@gmail.com, 2
prjain@sgsits.ac.in, 3
ajnards@gmail.com
Abstract:- This paper investigate the performance of
Instrumentation amplifier (INA) using three operational
Amplifier. The proposed circuit works for low input voltage
equalised to the heart beat of the human being to analyses the
ECG (Biomedical application) response. The analyses of
Gain, Bandwidth, Unity GBW, Phase margin and output
noise for operational amplifier used in INA and For the INA
Gain, Bandwidth, output noise and power Dissipation are
analysed. The proposed circuit designed on UMC 180nm
CMOS technology file and all the simulation done on
CADENCE SPECTRE Simulator.
Keyword: Amplifier basics, Differential Amplifier using
MOSFET, Operational Amplifier, Instrumentation Amplifier,
ECG (Biomedical application), Analog Electronics.
I. INTRODUCTION
Today Biomedical Application play a vital role in the field
of Technology but, it is very challenging task to fetch the
biomedical signal because of very small amplitude and
frequency of few hertz. As the biomedical signal is very
small and equal to noise if it is difficult task to find it’s
presence. Like Heart Beat signal or Pulse Signal which are
very weak in nature [1, 2]. So, to overcome from this
problem we need proper amplification, modified Gain,
Higher Bandwidth and suppressed noise device like,
Instrumentation Amplifier. An instrumentation amplifier is
the one of the most effective block of Biomedical field
mainly used in some application such as ECG, Transducer
or sensor based biomedical devices, Microelectronics
Devices etc. It provides better amplification, good
linearity, Gain, Bandwidth and having properties of
suppressing noise from the weak biomedical signal.
Basically it constitute of two differential input and single
ended output. The basic building block of biomedical
device is shown below in the Fig.1
Fig. 1 Biomedical Signal Fetching and Detecting Device
The Amplifier used in the device shown above is an
Instrumentation Amplifier working over the Biomedical
signal, the Amplifier shows good CMRR, Gain, BW, Low
power dissipation [3] and Low noise. The Device shown
above with Instrumentation Amplifier provided digital
output pulse after analysing Bio-medical signal. The
Biomedical device such as ECG having quite similar
blocks shown in the Fig. 1 and Instrumentation Amplifier
play an important role in it.
In this paper, SECTION II and SECTION III describe the
operational amplifier and the proposed instrumentation
amplifier respectively. SECTION IV and SECTION V
describe the simulation results and conclusion respectively.
II. DESCRIPTION OF OPERATIONAL AMPLIFIER
FOR DESIGNING OF INA
The basic building block of proposed circuit is an
Operational amplifier. There are three operational
amplifiers used in the proposed INA. Each operational
amplifier is dual stage amplifier basically used to enhance
the gain of the INA. The schematic of operational amplifier
shown below in the Fig. 2.
Fig.2 Operational Amplifier for the Proposed INA
The operational amplifier consist [5] of two stages first
stage is gain stage and second stage is called output stage.
Basically, second stage enhances the gain and provides
frequency compensation through compensation
capacitance Cc. The nmos MOS transistor M1, M2 act as
the differential stage, pmos transistor M3,M4 act as current
mirror, M5, M6 and M8 are used for biasing. The output is
taken out from the output load capacitance, the relationship
between load capacitance CL and compensation
capacitance CC are shown below:-
CL ≥ 2.2Cc........................(1)
Aspect ratio i.e. (W/L ratio) of MOS transistor for the
operational amplifier shown below in the TABLE I:-
TABLE I
Aspect
ratio
M1,
M2
M3,
M4
M5,
M6
M7 M8
W/L
(µm/ µm)
3/.5 7/.5 12/1 87/.5 75/1
Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
33 NITTTR, Chandigarh EDIT-2015
High Gain, Low Noise Instrumentation
Amplifier Using Three Operational Amplifiers
for Weak Biomedical Signal
1
Amit Kumar Chidar, 2
Pramod Kumar Jain, 3
D.S Ajnar
1,2,3
Microelectronics and VLSI Design, E&I Department, S.G.S.I.T.S Indore, M.P, India
1
amitchidar08@gmail.com, 2
prjain@sgsits.ac.in, 3
ajnards@gmail.com
Abstract:- This paper investigate the performance of
Instrumentation amplifier (INA) using three operational
Amplifier. The proposed circuit works for low input voltage
equalised to the heart beat of the human being to analyses the
ECG (Biomedical application) response. The analyses of
Gain, Bandwidth, Unity GBW, Phase margin and output
noise for operational amplifier used in INA and For the INA
Gain, Bandwidth, output noise and power Dissipation are
analysed. The proposed circuit designed on UMC 180nm
CMOS technology file and all the simulation done on
CADENCE SPECTRE Simulator.
Keyword: Amplifier basics, Differential Amplifier using
MOSFET, Operational Amplifier, Instrumentation Amplifier,
ECG (Biomedical application), Analog Electronics.
I. INTRODUCTION
Today Biomedical Application play a vital role in the field
of Technology but, it is very challenging task to fetch the
biomedical signal because of very small amplitude and
frequency of few hertz. As the biomedical signal is very
small and equal to noise if it is difficult task to find it’s
presence. Like Heart Beat signal or Pulse Signal which are
very weak in nature [1, 2]. So, to overcome from this
problem we need proper amplification, modified Gain,
Higher Bandwidth and suppressed noise device like,
Instrumentation Amplifier. An instrumentation amplifier is
the one of the most effective block of Biomedical field
mainly used in some application such as ECG, Transducer
or sensor based biomedical devices, Microelectronics
Devices etc. It provides better amplification, good
linearity, Gain, Bandwidth and having properties of
suppressing noise from the weak biomedical signal.
Basically it constitute of two differential input and single
ended output. The basic building block of biomedical
device is shown below in the Fig.1
Fig. 1 Biomedical Signal Fetching and Detecting Device
The Amplifier used in the device shown above is an
Instrumentation Amplifier working over the Biomedical
signal, the Amplifier shows good CMRR, Gain, BW, Low
power dissipation [3] and Low noise. The Device shown
above with Instrumentation Amplifier provided digital
output pulse after analysing Bio-medical signal. The
Biomedical device such as ECG having quite similar
blocks shown in the Fig. 1 and Instrumentation Amplifier
play an important role in it.
In this paper, SECTION II and SECTION III describe the
operational amplifier and the proposed instrumentation
amplifier respectively. SECTION IV and SECTION V
describe the simulation results and conclusion respectively.
II. DESCRIPTION OF OPERATIONAL AMPLIFIER
FOR DESIGNING OF INA
The basic building block of proposed circuit is an
Operational amplifier. There are three operational
amplifiers used in the proposed INA. Each operational
amplifier is dual stage amplifier basically used to enhance
the gain of the INA. The schematic of operational amplifier
shown below in the Fig. 2.
Fig.2 Operational Amplifier for the Proposed INA
The operational amplifier consist [5] of two stages first
stage is gain stage and second stage is called output stage.
Basically, second stage enhances the gain and provides
frequency compensation through compensation
capacitance Cc. The nmos MOS transistor M1, M2 act as
the differential stage, pmos transistor M3,M4 act as current
mirror, M5, M6 and M8 are used for biasing. The output is
taken out from the output load capacitance, the relationship
between load capacitance CL and compensation
capacitance CC are shown below:-
CL ≥ 2.2Cc........................(1)
Aspect ratio i.e. (W/L ratio) of MOS transistor for the
operational amplifier shown below in the TABLE I:-
TABLE I
Aspect
ratio
M1,
M2
M3,
M4
M5,
M6
M7 M8
W/L
(µm/ µm)
3/.5 7/.5 12/1 87/.5 75/1

2. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
NITTTR, Chandigarh EDIT -2015 34
III. PROPOSED INSTRUMENTATION AMPLIFIER
The proposed Instrumentation Amplifier consist of three
operational amplifier and six resistor to carry out
maximum gain [6]. The schematic of proposed circuit
shown below in the Fig.3
Fig. 3 Proposed Instrumentation Amplifier (INA)
The proposed circuit are basically used to amplifying small
or weak signals of few volts i.e. (0.5mv-4mv) range at
some common mode voltage range [4]. The output and
differential input voltage relationship for INA are shown
below:-
= −( − ) ∗ ((1 + 2 ) ).............(2)
The resistances of the proposed circuit can be designed
through the nmos transistor by which the chip area can be
reduced.
IV. SIMULATION RESULTS
The proposed circuit is designed on UMC 180nm CMOS
technology file using cadence tool. All the simulated
results related to Operational Amplifier and Proposed INA
is obtained by SPECTRE SIMULATOR tool. The
simulated results for Operational Amplifier are shown
below from Fig. 4 to Fig. 6.
Fig. 4 Operational Amplifier Gain
Fig.5 3-dB Bandwidth of Operational Amplifier
Fig.6 Phase Margin and Unity GBW
The related results for Operational Amplifier are shown in
the TABLE II.
TABLE II
Results for Operational Amplifier
PARAMETERS Result Obtained
Technology 180 nm
Supply voltage 1.8 v
Gain 67.083 dB
3-dB Bandwidth 11.496 KHz
Unity GBW 25.2678 MHz
Phase Margin 63.858 deg
B. Simulated Results for Proposed Instrumentation
Amplifier (INA)
All the Simulation results for proposed INA i.e. Gain, 3-dB
Bandwidth and output referred noise are shown below in
the Fig. 7, Fig. 8 and Fig. 9 respectively. All results are
obtained by using SPECTRE SIMULATOR tool.
Fig.7 Gain of proposed INA
Fig.8 3-dB Bandwidth of Proposed INA
Fig.9
Output Referred Noise (V/sqrt(Hz))
The related results for INA are shown below in the TABLE III.
Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
NITTTR, Chandigarh EDIT -2015 34
III. PROPOSED INSTRUMENTATION AMPLIFIER
The proposed Instrumentation Amplifier consist of three
operational amplifier and six resistor to carry out
maximum gain [6]. The schematic of proposed circuit
shown below in the Fig.3
Fig. 3 Proposed Instrumentation Amplifier (INA)
The proposed circuit are basically used to amplifying small
or weak signals of few volts i.e. (0.5mv-4mv) range at
some common mode voltage range [4]. The output and
differential input voltage relationship for INA are shown
below:-
= −( − ) ∗ ((1 + 2 ) ).............(2)
The resistances of the proposed circuit can be designed
through the nmos transistor by which the chip area can be
reduced.
IV. SIMULATION RESULTS
The proposed circuit is designed on UMC 180nm CMOS
technology file using cadence tool. All the simulated
results related to Operational Amplifier and Proposed INA
is obtained by SPECTRE SIMULATOR tool. The
simulated results for Operational Amplifier are shown
below from Fig. 4 to Fig. 6.
Fig. 4 Operational Amplifier Gain
Fig.5 3-dB Bandwidth of Operational Amplifier
Fig.6 Phase Margin and Unity GBW
The related results for Operational Amplifier are shown in
the TABLE II.
TABLE II
Results for Operational Amplifier
PARAMETERS Result Obtained
Technology 180 nm
Supply voltage 1.8 v
Gain 67.083 dB
3-dB Bandwidth 11.496 KHz
Unity GBW 25.2678 MHz
Phase Margin 63.858 deg
B. Simulated Results for Proposed Instrumentation
Amplifier (INA)
All the Simulation results for proposed INA i.e. Gain, 3-dB
Bandwidth and output referred noise are shown below in
the Fig. 7, Fig. 8 and Fig. 9 respectively. All results are
obtained by using SPECTRE SIMULATOR tool.
Fig.7 Gain of proposed INA
Fig.8 3-dB Bandwidth of Proposed INA
Fig.9
Output Referred Noise (V/sqrt(Hz))
The related results for INA are shown below in the TABLE III.
Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
NITTTR, Chandigarh EDIT -2015 34
III. PROPOSED INSTRUMENTATION AMPLIFIER
The proposed Instrumentation Amplifier consist of three
operational amplifier and six resistor to carry out
maximum gain [6]. The schematic of proposed circuit
shown below in the Fig.3
Fig. 3 Proposed Instrumentation Amplifier (INA)
The proposed circuit are basically used to amplifying small
or weak signals of few volts i.e. (0.5mv-4mv) range at
some common mode voltage range [4]. The output and
differential input voltage relationship for INA are shown
below:-
= −( − ) ∗ ((1 + 2 ) ).............(2)
The resistances of the proposed circuit can be designed
through the nmos transistor by which the chip area can be
reduced.
IV. SIMULATION RESULTS
The proposed circuit is designed on UMC 180nm CMOS
technology file using cadence tool. All the simulated
results related to Operational Amplifier and Proposed INA
is obtained by SPECTRE SIMULATOR tool. The
simulated results for Operational Amplifier are shown
below from Fig. 4 to Fig. 6.
Fig. 4 Operational Amplifier Gain
Fig.5 3-dB Bandwidth of Operational Amplifier
Fig.6 Phase Margin and Unity GBW
The related results for Operational Amplifier are shown in
the TABLE II.
TABLE II
Results for Operational Amplifier
PARAMETERS Result Obtained
Technology 180 nm
Supply voltage 1.8 v
Gain 67.083 dB
3-dB Bandwidth 11.496 KHz
Unity GBW 25.2678 MHz
Phase Margin 63.858 deg
B. Simulated Results for Proposed Instrumentation
Amplifier (INA)
All the Simulation results for proposed INA i.e. Gain, 3-dB
Bandwidth and output referred noise are shown below in
the Fig. 7, Fig. 8 and Fig. 9 respectively. All results are
obtained by using SPECTRE SIMULATOR tool.
Fig.7 Gain of proposed INA
Fig.8 3-dB Bandwidth of Proposed INA
Fig.9
Output Referred Noise (V/sqrt(Hz))
The related results for INA are shown below in the TABLE III.

3. Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426
35 NITTTR, Chandigarh EDIT-2015
TABLE III
Results for Proposed Instrumentation Amplifier
PARAMETER This
work
[4] [6] [7]
Technology (um) 0.18 0.18 0.5 0.8
Supply voltage 1.8v N/A N/A N/A
Gain (dB) 42.330 19.6 19.9 40
Bandwidth 135.91
KHz
N/A N/A N/A
Output noise
(V**
2/(Hz))
3.05µ N/A N/A N/A
Power dissipation 0.792m
W
N/A N/A 122u
V. CONCLUSION
The proposed Instrumentation Amplifier basically used for
amplifying the small amplitude and low frequency signal
equalized to heart beat or pulse. The designed circuit
shows high gain, low power dissipation and smaller area
wise. The supply voltage of 1.8 volts required for the
circuit. All the simulation results are clearly obtained by
the help of cadence spectre simulator.
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Shojaei-Baghini, M.; Lal, R.K.; and Sharma, D.K., “An ultra low power
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Philip E. Allen and Douglas R.Holberg, CMOS Analog Circuit Design,
Oxford University Press, pp 180-196, March 2002.
Chih-Jen Yen ; Wen-Yaw Chung and Mely Chen Chi ,“Micro-Power
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Applications”,IEEE Transactions On Circuits And Systems-I:Regular
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Ananth, R.S. and Lee, E.K., “Design of a low power implantable
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Systems (ISCAS’04), vol 4, pp. 9-12, 2004.