Voltage reference circuit with temperature compensation
A voltage reference circuit with temperature compensation includes a power supply, a reference voltage supply, a first PMOS transistor with its source connected to the power supply voltage, a second PMOS transistor with its source connected to the power supply and its gate and drain connected to the first PMOS gate, a first NMOS transistor with its gate and drain connected the first PMOS drain, a second NMOS transistor with its drain connected to the second PMOS drain and its gate connected with the first NMOS gate to the reference voltage supply, a resistor connected to the second NMOS source and ground, and an op-amp with its inverting input and its output connected the first NMOS source and its non-inverting input connected to the ground. In another aspect, a voltage reference circuit output is coupled to an NMOS gate in saturation mode connected to another voltage reference circuit.
1. A voltage reference circuit with temperature compensation, comprising:
a power supply;
a reference voltage supply;
a first PMOS transistor with a source connected to the power supply;
a second PMOS transistor with a source connected to the power supply and a gate and a drain connected together to the gate of the first PMOS;
a first NMOS transistor with a gate and a drain connected together to the drain of the first PMOS transistor;
a second NMOS transistor with a drain connected to the drain of the second PMOS transistor and a gate connected together with the gate of the first NMOS transistor to the reference voltage supply;
a resistor connected to the source of the second NMOS transistor and ground; and
an op-amp having one inverting input, one non-inverting input, and an op-amp output, wherein the op-amp inverting input and the op-amp output are connected together to the source of the first NMOS transistor, and the op-amp non-inverting input is connected to the ground.
2. The voltage reference circuit of claim 1 , wherein the op-amp has a limited gain configured to be adjustable.
3. The voltage reference circuit of claim 1 , wherein the first NMOS transistor and the second NMOS transistor have a size proportion ratio of 1:K, wherein the size proportion is defined as a width over a length of a channel of a transistor and K is a number greater than 1.
4. The voltage reference circuit of claim 3 , wherein K ranges 4-6.
5. The voltage reference circuit of claim 3 , wherein K ranges from 4 to 16.
6. The voltage reference circuit of claim 1 , wherein the resistor has a resistance ranging 1-40 kΩ.
7. The voltage reference circuit of claim 1 , wherein the reference voltage supply is expressed by:
VREF
NEW
1
=
(
VirtualVSS
)
+
(
V
TH
+
2
I
ref
μ
N
C
ox
(
W
L
)
N
)
where VREF NEW1 is the reference voltage supply, VirtualVSS is the op-amp output, V TH is the threshold voltage of the second NMOS transistor, I ref is the reference current of the voltage reference circuit, μ N is the mobility of the second NMOS transistor, C ox is the gate oxide capacitance of the second NMOS transistor, W is the width of the channel of the second NMOS transistor, L is the length of the channel of the second NMOS transistor and N is an integer greater than 1.
8. A voltage reference circuit with temperature compensation, comprising:
a power supply;
a reference voltage supply;
a first PMOS transistor with a source connected to the power supply;
a second PMOS transistor with a source connected to the power supply and a gate and a drain connected together to the gate of the first PMOS;
a first NMOS transistor with a gate and a drain connected together to the drain of the first PMOS transistor;
a second NMOS transistor with a drain connected to the drain of the second PMOS transistor and a gate connected together with the gate of the first NMOS transistor to the reference voltage supply;
a resistor connected to the source of the second NMOS transistor and ground; and
an op-amp having one inverting input, one non-inverting input, and an op-amp output, wherein the op-amp inverting input and the op-amp output are connected together to the source of the first NMOS transistor, the op-amp non-inverting input is connected to the ground, the op-amp has an adjustable gain.
9. The voltage reference circuit of claim 8 , wherein the first NMOS transistor and the second NMOS transistor have a size proportion ratio of 1:K, wherein the size proportion is defined as a width over a length of a channel of a transistor and K is a number greater than 1.
10. The voltage reference circuit of claim 9 , wherein K ranges 4-16.
11. The voltage reference circuit of claim 8 , wherein the resistor has a resistance ranging 1-40 kΩ.
12. The voltage reference circuit of claim 8 , wherein the reference voltage supply is expressed by:
VREF
NEW
1
=
(
VirtualVSS
)
+
(
V
TH
+
2
I
ref
μ
N
C
ox
(
W
L
)
N
)
where VREF NEW1 is the reference voltage supply, VirtualVSS is the op-amp output, V TH is the threshold voltage of the second NMOS transistor, I ref is the reference current of the voltage reference circuit, μN is the mobility of the second NMOS transistor, C ox is the gate oxide capacitance of the second NMOS transistor, W is the width of the channel of the second NMOS transistor, L is the length of the channel of the second NMOS transistor and N is an integer greater than 1.
13. The voltage reference circuit of claim 12 , wherein the reference current ranges from 2 microAmps (μA) to 10 μA.
14. A voltage reference circuit with temperature compensation, comprising:
a power supply;
a reference voltage supply;
a first PMOS transistor with a source connected to the power supply;
a second PMOS transistor with a source connected to the power supply and a gate and a drain connected together to the gate of the first PMOS;
a first NMOS transistor with a gate and a drain connected together to the drain of the first PMOS transistor;
a second NMOS transistor with a drain connected to the drain of the second PMOS transistor and a gate connected together with the gate of the first NMOS transistor to the reference voltage supply;
a resistor connected to the source of the second NMOS transistor and ground; and an op-amp having one inverting input, one non-inverting input, and an op-amp output,
wherein the op-amp inverting input and the op-amp output are connected together to the source of the first NMOS transistor, and the op-amp non-inverting input is connected to the ground, wherein the reference voltage supply is expressed by:
VREF
NEW
1
=
(
VirtualVSS
)
+
(
V
TH
+
2
I
ref
μ
N
C
ox
(
W
L
)
N
)
where VREF New1 is the reference voltage supply, VirtualVSS is the op-amp output, V TH is the threshold voltage of the second NMOS transistor, I ref is the reference current of the voltage reference circuit, μ N is the mobility of the second NMOS transistor, C ox is the gate oxide capacitance of the second NMOS transistor, W is the width of the channel of the second NMOS transistor, L is the length of the channel of the second NMOS transistor and N is an integer greater than 1.
15. The voltage reference circuit of claim 14 , wherein the op-amp has an adjustable gain.
16. The voltage reference circuit of claim 14 , wherein the first NMOS transistor and the second NMOS transistor have a size proportion ratio of 1:K, wherein the size proportion is defined as a width over a length of a channel of a transistor and K is a number greater than 1.
17. The voltage reference circuit of claim 16 , wherein K ranges from 4 to 16.
18. The voltage reference circuit of claim 14 , wherein the resistor has a resistance ranging 1-40 kΩ.
19. The voltage reference circuit of claim 14 , wherein the reference current of the voltage reference circuit is expressed by:
I
ref
R
S
=
2
I
ref
μ
N
C
ox
(
W
L
)
N
(
1
-
1
K
)
.
20. The voltage reference circuit of claim 14 , wherein the reference current ranges from 2 microAmps (μA) to 10 μA.