Temperature Compensated current reference

1. TEMPERATURE COMPENSATED
CURRENT REFERENCE
PRESENTED BY:
PANKAJ PAKHARE
ANUBHAV SRIVASTAVA
SUBMITED TO:
PROF . S. QURESHI

2. WHY CURRENT REFERENCE?
 Easy to implement analog circuit in current mode
 Arithmetic operation through current mode require lesser
power and area
 Requires lesser hardware

3. About circuit
• Consists of 12 MOSFETs
• Operating temperature ranges from 27°C to 125°
• Current Generator: 35μA
• Requires no diodes and resistors
• Presence of MOSFET improve the overall performance

4. Block Diagram

5. Current Generation Circuit
 Consists of two transistors : NMOS and PMOS
 Both are operating in saturation region
 PMOS transistor is current source
 NMOS transistor is diode connected
 Dimensions of transistors are chosen so that current of 40uA flows
through them

6. Bias Generation Circuit
 Bias voltage should vary as little as possible with temperature
 It is a voltage divider circuit
 Consists of 3 diode connected PMOS transistor
 Characteristics of transistors vary the same way over process
variation

7. Correction Circuit
 Consists of 3 transistors M6 ,M7 and M8
 M6 is current mirror with respect to NMOS in current generation
circuit
 M6 is made longer than M1 to reduce CLM
 M7 and M8 provide counter to variation in current

8. Widlar Current Mirror Circuit
 Consists of 4 transistors
 Used to further reduce the variation in current
 Generate small current with positive temperature coefficient
 This current is added with the current from current generation
circuit
Total current is fed to correction circuit.

9. Complete circuit diagram

10. Symbol

11. Output Current

12. Conclusion
The transistor-level circuit for the generation of a 35uA current
reference is designed
Proposed designed can be used for generation of currrent from uA
to mA

13. Reference
B. Razavi, Design of Analog CMOS Integrated Circuits. New York: McGraw-
Hill, 2001.
Design of Temperature Independent MOSFET only Current Reference by
Utthej Nukala