Bias circuit with threshold voltage change compensation function and temperature change compensation function

1. A bias circuit which applies a bias voltage to a control terminal of a first active element for an RF signal amplification, comprising:

a threshold voltage change compensation circuit having a second active element and configured to compensate said bias voltage based on a change in threshold voltage of said first active element by using said second active element; and

a first temperature compensation circuit connected between said control terminal and said voltage change compensation circuit and configured to compensate a change in said bias voltage based on a temperature change,

wherein said threshold voltage change compensation circuit comprises a first resistance connected with said second active element, and

wherein said threshold voltage change compensation circuit further comprises a second temperature compensation circuit configured to compensate a first voltage of a first node between said first resistance and said second active element based on said temperature change.

2. The bias circuit according to claim 1 , wherein said first and second active elements are transistors.

3. The bias circuit according to claim 2 , wherein said first and second active elements are voltage controlled-type transistors.

4. The bias circuit according to claim 2 , wherein said first and second active elements are current controlled-type transistors.

5. The bias circuit according to claim 1 , wherein said second active element has a same threshold voltage as said first active element.

6. The bias circuit according to claim 1 , wherein said second temperature compensation circuit comprises a first diode circuit containing at least one diode.

7. A bias circuit which applies a bias voltage to a control terminal of a first active element for an RF signal amplification, comprising:

a threshold voltage change compensation circuit having a second active element and configured to compensate said bias voltage based on a change in threshold voltage of said first active element by using said second active element; and

a first temperature compensation circuit connected between said control terminal and said voltage change compensation circuit and configured to compensate a change in said bias voltage based on a temperature change,

wherein said threshold voltage change compensation circuit comprises a first resistance connected with said second active element, and

further comprising:

a second temperature compensation circuit interposed between said threshold voltage change compensation circuit and said first temperature compensation circuit to compensate a first voltage of a first node between said first resistance and said second active element based on said temperature change.

8. The bias circuit according to claim 7 , wherein said second temperature compensation circuit comprises a first diode circuit containing at least one diode.

9. The bias circuit according to claim 6 , wherein said diode in said first diode circuit is a Schottky diode or a diode with a negative temperature coefficient.

10. The bias circuit according to claim 8 , wherein said diode in said first diode circuit is a Schottky diode or a diode with a negative temperature coefficient.

11. The bias circuit according to claim 1 , wherein said first temperature compensation circuit comprises a second diode circuit containing at least one diode.

12. The bias circuit according to claim 11 , wherein said first temperature compensation circuit further comprises a second resistance connected with said second diode circuit.

13. The bias circuit according to claim 11 , wherein said diode in said second diode circuit is a Schottky diode or a diode with a negative temperature coefficient.

14. A bias circuit which applies a bias voltage to a control terminal of a first active element for an RF signal amplification, comprising:

a threshold voltage change compensation circuit having a second active element and configured to compensate said bias voltage based on a change in threshold voltage of said first active element by using said second active element; and

a first temperature compensation circuit connected between said control terminal and said voltage change compensation circuit and configured to compensate a change in said bias voltage based on a temperature change,

wherein said first temperature compensation circuit comprises a second diode circuit containing at least one diode,

wherein said first temperature compensation circuit further comprises a second resistance connected with said second diode circuit, and

wherein a second node between said second resistance and said second diode circuit is connected with said control terminal, and

said bias circuit further comprises:

an additional circuit comprising a third resistance and a third active element connected with said third resistance, connected with said first temperature compensation circuit on a lower voltage side of said first temperature compensation circuit.

15. The bias circuit according to claim 14 , wherein said additional circuit further comprises:

a third temperature compensation circuit configured to compensate a second voltage of a third node between said third resistance and said third active element based on said temperature change.

16. The bias circuit according to claim 15 , wherein said third temperature compensation circuit comprises a third diode circuit containing at least one diode.

17. The bias circuit according to claim 16 , wherein said diode in said second diode circuit is a Schottky diode or a diode with a negative temperature coefficient.

18. The bias circuit according to claim 14 , wherein said second and third active elements have a same threshold voltage as said first active element.