Mixed type frequency compensating circuit and control circuit

1. A mixed type frequency compensating circuit, comprising:

an integral component sub-circuit of a voltage-amplifier-type frequency compensating circuit configured to amplify an input voltage signal in a voltage mode and configured to perform a voltage regulation of a whole loop; and

a proportional component sub-circuit of a transconductance-amplifier-type frequency compensating circuit configured to amplify the input voltage signal in a current mode and configured to increase a phase margin for stability;

wherein the integral component sub-circuit comprises:

a first resistor configured to have a first terminal to which the input voltage signal is applied;

an operational amplifier configured to have a first input terminal coupled to a second terminal of the first resistor, a second input terminal to which the reference voltage is applied, and configured to amplify the input voltage signal in a voltage mode to generate a first amplified signal and provide the first amplified signal to a first output node; and

a first capacitor coupled between the first output node and the first input terminal of the operational amplifier.

2. The mixed type frequency compensating circuit of claim 1 , wherein the input voltage signal is generated based on an output voltage of a DC-DC converter.

3. The mixed type frequency compensating circuit of claim 1 , wherein the first capacitor is configured to have a capacitance less than or equal to 1.00 pF, and is configured to be includable in a semiconductor integrated circuit.

4. The mixed type frequency compensating circuit of claim 1 further comprising:

a third resistor coupled between the first input terminal of the transconductance amplifier and a low supply voltage; and

a fourth resistor having a first terminal coupled to the first input terminal of the transconductance amplifier and a second terminal to which the output voltage of the DC-DC converter is applied.

5. The mixed type frequency compensating circuit of claim 2 , wherein the proportional component sub-circuit comprises:

a transconductance amplifier configured to have a first input terminal to which the input voltage signal is applied, a second input terminal to which a reference voltage is applied, and configured to amplify the input voltage signal in a current mode to generate a second amplified signal and provide the second amplified signal to a second output node; and

a second resistor coupled between the second output node and the first output node.

6. The mixed type frequency compensating circuit of claim 5 , wherein the second resistor is configured to have a resistance less than or equal to 1 MΩ, and is configured to be includable in a semiconductor integrated circuit.

7. A control circuit comprising:

a mixed type frequency compensating circuit configured to amplify a feedback voltage signal to generate a compensating voltage signal;

a current detecting circuit configured to detect a current flowing through a switching transistor to generate a first detecting voltage signal;

a comparator configured to compare a voltage level of the compensating voltage signal with a voltage level of the first detecting voltage signal to generate a comparing signal; and

a pulse-width modulating circuit configured to generate a gate driving signal based on a clock signal and the comparing signal;

wherein the mixed type frequency compensating circuit comprises:

an integral component sub-circuit of a voltage-amplifier-type frequency compensating circuit configured to amplify an input voltage signal in a voltage mode and configured to perform frequency compensation; and

a proportional component sub-circuit of a transconductance-amplifier-type frequency compensating circuit configured to amplify an input voltage signal in a current mode and configured to perform frequency compensation; and

wherein the integral component sub-circuit comprises:

a first resistor configured to have a first terminal to which the input voltage signal is applied;

an operational amplifier configured to have a first input terminal coupled to a second terminal of the first resistor, a second input terminal to which the reference voltage is applied, and configured to amplify the input voltage signal in a voltage mode to generate a first amplified signal and provide the first amplified signal to a first output node; and

a first capacitor coupled between the first output node and the first input terminal of the operational amplifier.

8. The control circuit of claim 7 , wherein the pulse-width modulating circuit is configured to have a flip-flop.

9. The control circuit of claim 7 further comprising:

a buffer configured to buffer an output signal of the pulse-width modulating circuit to generate the gate driving signal.

10. The control circuit of claim 7 , wherein the feedback voltage signal is generated based on an output voltage of a DC-DC converter.

11. The control circuit of claim 7 , wherein the first capacitor is configured to have a capacitance less than or equal to 100 pF, and is configured to be includable in a semiconductor integrated circuit.

12. The control circuit of claim 7 , wherein the mixed type frequency compensating circuit further comprises:

a third resistor coupled between the first input terminal of the transconductance amplifier and a low supply voltage; and

a fourth resistor having a first terminal coupled to the first input terminal of the transconductance amplifier and a second terminal to which the output voltage of the DC-DC converter is applied.

13. The control circuit of claim 10 , wherein the proportional sub-circuit comprises:

a transconductance amplifier is configured to have a first input terminal to which the input voltage signal is applied, a second input terminal to which a reference voltage is applied, and configured to amplify the input voltage signal in a current mode to generate a second amplified signal and provide the second amplified signal to a second output node; and

a second resistor coupled between the second output node and the first output node.

14. The control circuit of claim 13 , wherein the second resistor is configured to have a resistance less than or equal to 1 MΩ, and is configured to be includable in a semiconductor integrated circuit.

15. A DC-DC converter comprising:

an input node to which a DC input voltage is applied;

a switching transistor coupled between the input node and a first node, and configured to be driven in response to a gate driving signal;

a diode configured to have a cathode coupled to the first node and an anode coupled to a first supply voltage;

an inductor coupled between the first node and an output node;

a first capacitor coupled between the output node and the first supply voltage; and

a control circuit including a mixed type frequency compensating circuit, the control circuit generating the gate driving signal in response to a current flowing through the switching transistor, a voltage of the output node, and a clock signal;

wherein the mixed type frequency compensating circuit comprises:

an integral component sub-circuit of a voltage-amplifier-type frequency compensating circuit configured to amplify an input voltage signal in a voltage mode and configured to perform frequency compensation; and

a proportional component sub-circuit of a transconductance-amplifier-type frequency compensating circuit configured to amplify the input voltage signal in a current mode and configured to perform frequency compensation; and

wherein the integral component sub-circuit comprises:

a first resistor configured to have a first terminal to which the input voltage signal is applied;

an operational amplifier configured to have a first input terminal coupled to a second terminal of the first resistor, a second input terminal to which the reference voltage is applied, and configured to amplify the input voltage signal in a voltage mode to generate a first amplified signal and provide the first amplified signal to a first output node; and

a first capacitor coupled between the first output node and the first input terminal of the operational amplifier.

16. The DC-DC converter of claim 15 , wherein the control circuit comprises:

a mixed type frequency compensating circuit configured to amplify a feedback voltage signal to generate a compensating voltage signal;

a current detecting circuit configured to detect a current flowing through a switching transistor to generate a first detecting voltage signal;

a comparator configured to compare a voltage level of the compensating voltage signal with a voltage level of the first detecting voltage signal to generate a comparing signal; and

a pulse-width modulating circuit configured to generate a gate driving signal based on a clock signal and the comparing signal.

17. The DC-DC converter of claim 15 , wherein the proportional component sub-circuit comprises:

a transconductance amplifier configured to have a first input terminal to which the input voltage signal is applied, a second input terminal to which a reference voltage is applied, and configured to amplify the input voltage signal in a current mode to generate a second amplified signal and provide the second amplified signal to a second output node; and

a second resistor coupled between the second output node and the first output node.

18. The DC-DC converter of claim 15 , wherein the mixed type frequency compensating circuit further comprises:

a voltage dividing circuit configured to divide a voltage of the output node to generate the feedback voltage signal.

19. The DC-DC converter of claim 16 , wherein the pulse-width modulating circuit is configured to have a flip-flop.

20. The DC-DC converter of claim 16 , wherein the control circuit further comprises:

a buffer configured to buffer an output signal of the pulse-width modulating circuit to generate the gate driving signal.

21. A method of controlling a mixed type frequency compensating circuit, the method comprising:

compensating a frequency characteristics of a feedback voltage signal using an integral component sub-circuit of a voltage-amplifier-type frequency compensating circuit; and

compensating the frequency characteristics of the feedback voltage signal using a proportional component sub-circuit of a transconductance-amplifier-type frequency compensating circuit;

wherein the integral component sub-circuit comprises:

a first resistor configured to have a first terminal to which the input voltage signal is applied;

an operational amplifier configured to have a first input terminal coupled to a second terminal of the first resistor, a second input terminal to which the reference voltage is applied, and configured to amplify the input voltage signal in a voltage mode to generate a first amplified signal and provide the first amplified signal to a first output node; and

a first capacitor coupled between the first output node and the first input terminal of the operational amplifier.

22. The method of claim 21 , wherein compensating the frequency characteristics of the feedback voltage signal using the integral component sub-circuit of the voltage-amplifier-type frequency compensating circuit comprises:

amplifying the feedback voltage signal in a voltage mode.

23. The method of claim 21 , wherein compensating the frequency characteristics of the feedback voltage signal using the proportional component sub-circuit of the transconductance-amplifier-type frequency compensating circuit comprises:

amplifying the feedback voltage signal in a current mode.

24. A method of controlling a DC-DC converter, the method comprising:

amplifying a feedback voltage signal in a voltage mode and in a current mode to generate a compensating voltage signal;

detecting a current flowing through a switching transistor to generate a first detecting voltage signal;

comparing a voltage level of the compensating voltage signal with a voltage level of the first detecting voltage signal to generate a comparing signal; and

generating a gate driving signal based on a clock signal and the comparing signal;

wherein the DC-DC converter comprises a mixed type frequency compensating circuit comprising:

an integral component sub-circuit of a voltage-amplifier-type frequency compensating circuit configured to amplify an input voltage signal in a voltage mode and configured to perform frequency compensation; and

a proportional component sub-circuit of a transconductance-amplifier-type frequency compensating circuit configured to amplify the input voltage signal in a current mode and configured to perform frequency compensation;

wherein the integral component sub-circuit comprises:

a first resistor configured to have a first terminal to which the input voltage signal is applied;

an operational amplifier configured to have a first input terminal coupled to a second terminal of the first resistor, a second input terminal to which the reference voltage is applied, and configured to amplify the input voltage signal in a voltage mode to generate a first amplified signal and provide the first amplified signal to a first output node; and

a first capacitor coupled between the first output node and the first input terminal of the operational amplifier.