#### Transcript Design of an Instrumentation Amplifier Instrumentation Amplifier Bias Voltage Generation Differential Pair with Active Load.

```Design of an
Instrumentation Amplifier
Instrumentation Amplifier
Bias Voltage Generation
Anatomy of a Different Pair with
Differential Pair
(Sec. 10.3)
Differential Pair
(Sec. 10.3)
Current Mirror
(Section 9.2)
Bias Voltage Generation
Schedule
Cascode (Section 9.1, 11/14)
Current Mirror (Section 9.2.3, 11/19)
Bias Circuitry (Handout, 11/26)
Differential Pair (Section 10.3, 11/28)
(Section 10.6, 12/3)
• Instrumentation Amplifier (12/5)
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Common Source Amplifier
Design
Design spec:
1 uA of bias current
AV=-30 V/V of gain.
Measure Peak to Peak Voltage
The gain is approximately 30.
Voltage Gain
Design Exploration
• Initial results
– ro1=2.228 Mohms
– ro2=5.32 Mohms
– Av=-31.4 V/V
– gmovergds1=44.57
– gmvoergds2=42.5
Design: If we can increase ro1, we can potentially raise the gain!
Cascode Circuit
Matlab Computation
ro2 is 1.526 Mohms
gmovergds_2=30 Mohms
Rout is 55.2 Mohms
Gain Calculation
We should be increase the gain from 30 to 97.
DC of Vout is too low!
The gate bias voltage
for T0=284.4 mV
The gate bias voltage
For T1 is 0.33 V +0.3 V
0.63 V
The output voltage does
Is only 71.87 mV
What happens?
Calculate the Gain of a Circuit
Using Norton Equivalent Circuit
Short Circuit Transconductrance
Sweep DC Voltage
Copy from Cellview
Define DC voltage as a variable.
Setup the Sweep
Run Parametric Analysis
Use Sweep to Zoom on the
Correct Gate Bias Voltage
We want to keep the output voltage close to 0.6 V.