Amplitude converting circuit

• US 6,861,889 B2
• Filed: 02/26/2002
• Issued: 03/01/2005
• Est. Priority Date: 02/26/2002
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Tobita, Youichi
• Primary Examiner(s): NGUYEN, LONG T
• Application Number:
  US10/450,268
• Publication Number:
  US 20040041614A1
• Time in Patent Office: 1,099 Days
• Field of Search: 327/55, 327/57, 327/333, 327/390, 327/108, 327/427, 327/589, 326/68, 326/80, 326/81, 326/83, 326/88
• US Class Current: 327/333
• CPC Class Codes: G09G 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: H03K 17/063 in field-effect transistor switches
• CPC Class Codes: H03K 3/356113 using additional transistors in the input circuit

Abstract

A level shifter includes first and second P type thin film transistors (TFTs) and first and second N type TFTs for latching levels of first and second output nodes, third and fourth N type TFTs for setting levels of the first and second output nodes, and first and second resistance elements and first and second capacitors for applying, between the gate-source of the third and fourth N type TFTs, a voltage higher than a voltage of an input signal, in response to rising and falling edges of the input signal respectively.

Claims

1. An amplitude converting circuit converting a first signal, having a first voltage as an amplitude, to a second voltage, having a second voltage as an amplitude, the second voltage being higher than the first voltage, the circuit comprising:

first and second transistors of a first conductivity type, receiving at respective first electrodes the second voltage, and having second electrodes connected to first and second output nodes for outputting the second signal and a complement of the second signal, respectively, and input electrodes connected to the second and first output nodes, respectively;

third and fourth transistors of a second conductivity type having first electrodes connected to the first and second output nodes, respectively; and

a driving circuit driven by the first signal and a complement of the first signal, applying a third voltage, higher than the first voltage, between an input electrode and a second electrode of said third transistor, in response to a leading edge of the first signal, to render said third transistor conductive, and applying the third voltage between an input electrode and a second electrode of said fourth transistor, in response to a trailing edge of the first signal, to render said fourth transistor conductive, said driving circuit including

a first resistance element connected between the input electrode and the second electrode of said third transistor,

a first capacitor having a first electrode receiving the complement of the first signal and a second electrode connected to the input electrode of said third transistor,

a second resistance element connected between the input electrode and the second electrode of said fourth transistor, and

a second capacitor having a first electrode receiving the first signal and a second electrode connected to the input electrode of said fourth transistor.

2. The amplitude converting circuit according to claim 1, wherein

said first resistance element includes a fifth transistor connected between the input electrode and the second electrode of said third transistor and receiving at an input electrode a fourth voltage;

and

said second resistance element includes a sixth transistor connected between the input electrode and the second electrode of said fourth transistor and receiving at an input electrode the fourth voltage.

3. The amplitude converting circuit according to claim 2, wherein

said fifth and sixth transistors are of the second conductivity type;

and

the fourth voltage is equal to the second voltage.

4. The amplitude converting circuit according to claim 1, wherein

said first resistance element includes a fifth transistor connected between the input electrode and the second electrode of said third transistor;

said second resistance element includes a sixth transistor connected between the input electrode and the second electrode of said fourth transistor; and

said driving circuit further includes a pulse generating circuit generating pulses temporarily increasing resistance of said fifth transistor in response to a leading edge of the first signal and temporarily increasing resistance of said sixth transistor in response to a trailing edge of the first signal.

5. The amplitude converting circuit according to claim 4, wherein

said fifth and sixth transistors are of the second conductivity type;

and

said pulse generating circuit includes

a third resistance element connected between a node at a fourth voltage, having the same polarity as the second voltage, and the input electrode of said fifth transistor,

a third capacitor having a first electrode receiving the first signal and a second electrode connected to the input electrode of said fifth transistor,

a fourth resistance element connected between the node at the fourth voltage and the input electrode of said sixth transistor, and

a fourth capacitor having a first electrode receiving the complement of the first signal and a second electrode connected to the input electrode said sixth transistor.

6. The amplitude converting circuit according to claim 5, wherein the fourth voltage is equal to the second voltage.

7. The amplitude converting circuit according to claim 4, wherein

said fifth and sixth transistors are of the first conductivity type;

and

said pulse generating circuit includes

a third resistance element connected between a node at a fourth voltage, of polarity opposite to that of the second voltage, and the input electrode of said fifth transistor,

a third capacitor having a first electrode receiving the complement of said first signal and a second electrode connected to the input electrode of said fifth transistor,

a fourth resistance element connected between the node at the fourth voltage and the input electrode of said sixth transistor, and

a fourth capacitor having a first electrode receiving the first signal and a second electrode connected to the input electrode of said sixth transistor.

8. The amplitude converting circuit according to claim 1, wherein said driving circuit further includes

a first diode element connected between the second electrode and the input electrode of said third transistor, and

a second diode element connected between the second electrode and the input electrode of said fourth transistor.

9. The amplitude converting circuit according to claim 1, further comprising a latch circuit for latching potentials of the first and second output nodes.

10. The amplitude converting circuit according to claim 9, wherein said latch circuit includes fifth and sixth transistors of the second conductivity type, having first electrodes connected to the first and second output nodes, respectively, second electrodes receiving the first signal and the complement of the first signal, respectively, and input electrodes connected to the second and first output nodes, respectively.

11. The amplitude converting circuit according to claim 9, wherein said latch circuit includes fifth and sixth transistors of the second conductivity type, connected between the first and second output nodes and a node at a reference potential, respectively, and having input electrodes connected to the second and first output nodes, respectively.

12. The amplitude converting circuit according to claim 9, wherein said first, second, third, and fourth transistors are thin film transistors.

13. The amplitude converting circuit according to claim 1, further comprising:

a fifth transistor of the first conductivity type inserted between the second electrode of said first transistor and the first output node and having an input electrode connected to the input electrode of said third transistor; and

a sixth transistor of the first conductivity type inserted between the second electrode of said second transistor and the second output node and having an input electrode connected to the input electrode of said fourth transistor.

14. The amplitude converting circuit according to claim 1, wherein said first, second, third, and fourth transistors are thin film transistors.

15. An amplitude converting circuit converting a first signal, having a first voltage as an amplitude, to a second voltage, having a second voltage as an amplitude, the second voltage being higher than the first voltage, the circuit comprising:

first and second transistors of a first conductivity type, receiving at respective first electrodes the second voltage, and having second electrodes connected to first and second output nodes for outputting the second signal and a complement of the second signal, respectively, and input electrodes connected to the second and first output nodes, respectively;

third and fourth transistors of a second conductivity type having first electrodes connected to the first and second output nodes, respectively; and

a driving circuit driven by the first signal and a complement of the first signal, applying a third voltage, higher than the first voltage, between an input electrode and a second electrode of said third transistor, in response to a leading edge of the first signal, to render said third transistor conductive, and applying the third voltage between an input electrode and a second electrode of said fourth transistor, in response to a trailing edge of the first signal, to render said fourth transistor conductive, said driving circuit including

a first resistance element connected between the second electrode of said third transistor and a node at a reference voltage,

a first capacitor having a first electrode receiving the first signal and a second electrode connected to the second electrode of said third transistor,

a second resistance element connected between the second electrode of said fourth transistor and the node at the reference voltage, and

a second capacitor having a first electrode receiving the complement of the first signal and a second electrode connected to the second electrode of said fourth transistor.

16. The amplitude converting circuit according to claim 15, wherein

said first resistance element includes a fifth transistor connected between the second electrode of said third transistor and the node at the reference voltage;

said second resistance element includes a sixth transistor connected between the second electrode of said fourth transistor and the node at the reference voltage; and

said driving circuit further includes a pulse generating circuit generating pulses temporarily increasing resistance of said fifth transistor in response to leading edge of the first signal and temporarily increasing resistance of said sixth transistor in response to a trailing edge of the first signal.

17. The amplitude converting circuit according to claim 16, wherein

said fifth and sixth transistors are of the second conductivity type;

and

said pulse generating circuit includes

a third resistance element connected between a node at a fourth voltage, having the same polarity as the second voltage, and the input electrode of said fifth transistor,

a third capacitor having a first electrode receiving the first signal and a second electrode connected to the input electrode of said fifth transistor,

a fourth resistance element connected between the node at the fourth voltage and the input electrode of said sixth transistor, and

a fourth capacitor having a first electrode receiving the complement of the first signal and a second electrode connected to the input electrode of said sixth transistor.

18. The amplitude converting circuit according to claim 17, wherein the fourth voltage is equal to the second voltage.

19. The amplitude converting circuit according to claim 15, wherein said first, second, third, and fourth transistors are thin film transistors.

20. The amplitude converting circuit according to claim 15, further comprising a latch circuit for latching potentials of the first and second output nodes.

21. The amplitude converting circuit according to claim 20, wherein said latch circuit includes fifth and sixth transistors of the second conductivity type, having first electrodes connected to the first and second output nodes, respectively, second electrodes receiving the first signal and the complement of the first signal, respectively, and input electrodes connected to the second and first output nodes, respectively.

22. The amplitude converting circuit according to claim 20, wherein said latch circuit includes fifth and sixth transistors of the second conductivity type, connected between the first and second output nodes and a node at a reference potential, respectively, and having input electrodes connected to the second and first output nodes, respectively.

23. The amplitude converting circuit according to claim 15, further comprising:

a fifth transistor of the first conductivity type inserted between the second electrode of said first transistor and the first output node and having an input electrode connected to the input electrode of said third transistor; and

a sixth transistor of the first conductivity type inserted between the second electrode of said second transistor and the second output node and having an input electrode connected to the input electrode of said fourth transistor.