Low noise logic amplifier with nondifferential to differential conversion

• US 5,343,094 A
• Filed: 01/13/1993
• Issued: 08/30/1994
• Est. Priority Date: 01/13/1993
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Nguyen, Thai M.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): ROSEEN, RICHARD R
• Application Number:
  US08/004,136
• Time in Patent Office: 594 Days
• Field of Search: 307/475, 307/473, 307/443
• US Class Current: 326/63
• CPC Class Codes: H03K 19/00346 Modifications for eliminating interference or parasitic voltages or currents
• CPC Class Codes: H03K 19/017527 with at least one differential stage
• CPC Class Codes: H03K 5/023 using field effect transistors
• CPC Class Codes: H03K 5/151 with two complementary outputs
• CPC Class Codes: H03K 5/2481 with at least one differential stage

Abstract

A low noise logic amplifier with an input signal converter and a differential logic amplifier which together receive and convert a nondifferential input logic signal to a differential output logic signal. The input signal converter receives the nondifferential logic signal and converts it to a differential input logic signal for the differential logic amplifier. The differential logic amplifier has two output signal current paths for its bias current. The input signal converter provides the differential input logic signal with a delay between its two differential logic phases such that at least one of the two output signal current paths in the differential logic amplifier is continuously conducting the bias current. Thus, during generation of the differential output logic signal, regardless of whether the differential input logic signal is experiencing a high-to-low or low-to-high logic transition, the differential logic amplifier bias current flows continuously and without interruption, thereby minimizing generation of noise spikes from abrupt changes in bias current flow.

Claims

1. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

differential logic amplifier means for receiving a bias current and a first differential logic signal, and in accordance therewith generating a second differential logic signal, wherein said differential logic amplifier means includes a plurality of output signal current paths of which each is selectively conductive for said bias current; and

input converter means coupled to said differential logic amplifier means for receiving and converting a nondifferential logic signal to provide said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein at least one of said plurality of output signal current paths is conductive for said bias current uninterruptedly during said high-to-low and low-to-high logic transitions.

2. A logic amplifier as recited in claim 1, wherein said differential logic amplifier means comprises a plurality of source-coupled metal oxide semiconductor field effect transistors.

3. A logic amplifier as recited in claim 1, wherein said input converter means comprises a plurality of cross-coupled NAND gates.

4. A logic amplifier as recited in claim 1, wherein said input converter means comprises a plurality of cross-coupled NOR gates.

5. A logic amplifier as recited in claim 1, further comprising output converter means coupled to said differential logic amplifier means for receiving and converting said second differential logic signal to a third differential logic signal.

6. A logic amplifier as recited in claim 5, wherein said output converter means comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

7. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

differential logic amplifier means for receiving a bias current, a nondifferential logic signal and a first differential logic signal, and in accordance therewith generating a second differential logic signal, wherein said differential logic amplifier means includes a plurality of output signal current paths of which each is selectively conductive for said bias current; and

input converter means coupled to said differential logic amplifier means for receiving and converting said nondifferential logic signal to provide said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein at least one of said plurality of output signal current paths is conductive for said bias current uninterruptedly during said high-to-low and low-to-high logic transitions.

8. A logic amplifier as recited in claim 7, wherein said differential logic amplifier means comprises a plurality of source-coupled metal oxide semiconductor field effect transistors.

9. A logic amplifier as recited in claim 7, wherein said input converter means comprises a plurality of serially-coupled inverters.

10. A logic amplifier as recited in claim 7, further comprising output converter means coupled to said differential logic amplifier means for receiving and converting said second differential logic signal to a third differential logic signal.

11. A logic amplifier as recited in claim 10, wherein said output converter means comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

12. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

a differential logic amplifier which includes a bias port for receiving a bias current, an input port for receiving a first differential logic signal, an output port for providing a second differential logic signal and a plurality of output signal current paths connected to said bias port, wherein each one of said plurality of output signal current paths is selectively conductive for said bias current; and

an input amplifier which includes an input port for receiving a nondifferential logic signal and an output port coupled to said differential logic amplifier input port for providing said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein at least one of said plurality of output signal current paths is conductive for said bias current uninterruptedly during said high-to-low and low-to-high logic transitions.

13. A logic amplifier as recited in claim 12, wherein said differential logic amplifier comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled and said bias port comprises said mutually coupled source terminals.

14. A logic amplifier as recited in claim 12, wherein said input amplifier comprises a plurality of cross-coupled NAND gates.

15. A logic amplifier as recited in claim 12, wherein said input amplifier comprises a plurality of cross-coupled NOR gates.

16. A logic amplifier as recited in claim 12, further comprising an output amplifier which includes an input port coupled to said differential logic amplifier output port for receiving said second differential logic signal and includes an output port for providing a third differential logic signal.

17. A logic amplifier as recited in claim 16, wherein said output amplifier comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

18. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

a differential logic amplifier which includes a bias port for receiving a bias current, a nondifferential input port for receiving a nondifferential logic signal, a differential input port for receiving a first differential logic signal, an output port for providing a second differential logic signal and a plurality of output signal current paths connected to said bias port, wherein each one of said plurality of output signal current paths is selectively conductive for said bias current; and

an input amplifier which includes an input port for receiving said nondifferential logic signal and an output port coupled to said differential logic amplifier differential input port for providing said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein at least one of said plurality of output signal current paths is conductive for said bias current uninterruptedly during said high-to-low and low-to-high logic transitions.

19. A logic amplifier as recited in claim 18, wherein said differential logic amplifier comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled and said bias port comprises said mutually coupled source terminals.

20. A logic amplifier as recited in claim 18, wherein said input amplifier comprises a plurality of serially-coupled inverters.

21. A logic amplifier as recited in claim 18, further comprising an output amplifier which includes an input port coupled to said differential logic amplifier output port for receiving said second differential logic signal and includes an output port for providing a third differential logic signal.

22. A logic amplifier as recited in claim 21, wherein said output amplifier comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

23. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

differential logic amplifier means for receiving a bias current and a first differential logic signal, and in accordance therewith generating a second differential logic signal;

bias current source means coupled to said differential logic amplifier means for providing said bias current; and

input converter means coupled to said differential logic amplifier means for receiving and converting a nondifferential logic signal to provide said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein said bias current flows uninterruptedly through said differential logic amplifier means during said high-to-low and low-to-high logic transitions.

24. A logic amplifier as recited in claim 23, wherein said differential logic amplifier means comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled.

25. A logic amplifier as recited in claim 24, wherein said bias current source means comprises a tail current source coupled to said mutually coupled source terminals of said plurality of metal oxide semiconductor field effect transistors.

26. A logic amplifier as recited in claim 23, wherein said bias current source means comprises a tail current source.

27. A logic amplifier as recited in claim 23, wherein said input converter means comprises a plurality of cross-coupled NAND gates.

28. A logic amplifier as recited in claim 23, wherein said input converter means comprises a plurality of cross-coupled NOR gates.

29. A logic amplifier as recited in claim 23, further comprising output converter means coupled to said differential logic amplifier means for receiving and converting said second differential logic signal to a third differential logic signal.

30. A logic amplifier as recited in claim 29, wherein said output converter means comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

31. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

differential logic amplifier means for receiving a bias current, a nondifferential logic signal and a first differential logic signal, and in accordance therewith generating a second differential logic signal;

bias current source means coupled to said differential logic amplifier means for providing said bias current; and

input converter means coupled to said differential logic amplifier means for receiving and converting said nondifferential logic signal to provide said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein said bias current flows uninterruptedly through said differential logic amplifier means during said high-to-low and low-to-high logic transitions.

32. A logic amplifier as recited in claim 31, wherein said differential logic amplifier means comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled.

33. A logic amplifier as recited in claim 32, wherein said bias current source means comprises a tail current source coupled to said mutually coupled source terminals of said plurality of metal oxide semiconductor field effect transistors.

34. A logic amplifier as recited in claim 31, wherein said bias current source means comprises a tail current source.

35. A logic amplifier as recited in claim 31, wherein said input converter means comprises a plurality of serially-coupled inverters.

36. A logic amplifier as recited in claim 31, further comprising output converter means coupled to said differential logic amplifier means for receiving and converting said second differential logic signal to a third differential logic signal.

37. A logic amplifier as recited in claim 36, wherein said output converter means comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

38. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

a differential logic amplifier which includes a bias port for receiving a bias current, an input port for receiving a first differential logic signal and an output port for providing a second differential logic signal;

a bias current source which includes a current port coupled to said differential logic amplifier bias port for providing said bias current; and

an input amplifier which includes an input port for receiving a nondifferential logic signal and an output port coupled to said differential logic amplifier input port for providing said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein said bias current flows uninterruptedly through said differential logic amplifier during said high-to-low and low-to-high logic transitions.

39. A logic amplifier as recited in claim 38, wherein said differential logic amplifier comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled and said bias port comprises said mutually coupled source terminals.

40. A logic amplifier as recited in claim 39, wherein said bias current source means comprises a tail current source.

41. A logic amplifier as recited in claim 38, wherein said bias current source means comprises a tail current source.

42. A logic amplifier as recited in claim 38, wherein said input amplifier comprises a plurality of cross-coupled NAND gates.

43. A logic amplifier as recited in claim 38, wherein said input amplifier comprises a plurality of cross-coupled NOR gates.

44. A logic amplifier as recited in claim 38, further comprising an output amplifier which includes an input port coupled to said differential logic amplifier output port for receiving said second differential logic signal and includes an output port for providing a third differential logic signal.

45. A logic amplifier as recited in claim 44, wherein said output amplifier comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.

46. A logic amplifier for converting a nondifferential logic signal to a differential logic signal, comprising:

a differential logic amplifier which includes a bias port for receiving a bias current, a nondifferential input port for receiving a nondifferential logic signal, a differential input port for receiving a first differential logic signal and an output port for providing a second differential logic signal;

a bias current source which includes a current port coupled to said differential logic amplifier bias port for providing said bias current; and

an input amplifier which includes an input port for receiving said nondifferential logic signal and an output port coupled to said differential logic amplifier differential input port for providing said first differential logic signal;

wherein said first differential logic signal includes a plurality of signal phases with high and low logic levels having high-to-low and low-to-high logic transitions between said high and low logic levels, and further wherein said bias current flows uninterruptedly through said differential logic amplifier during said high-to-low and low-to-high logic transitions.

47. A logic amplifier as recited in claim 46, wherein said differential logic amplifier comprises a plurality of metal oxide semiconductor field effect transistors with source terminals which are mutually coupled and said bias port comprises said mutually coupled source terminals.

48. A logic amplifier as recited in claim 47, wherein said bias current source means comprises a tail current source.

49. A logic amplifier as recited in claim 46, wherein said bias current source means comprises a tail current source.

50. A logic amplifier as recited in claim 46, wherein said input amplifier comprises a plurality of serially-coupled inverters.

51. A logic amplifier as recited in claim 46, further comprising an output amplifier which includes an input port coupled to said differential logic amplifier output port for receiving said second differential logic signal and includes an output port for providing a third differential logic signal.

52. A logic amplifier as recited in claim 51, wherein said output amplifier comprises a plurality of bipolar junction transistors mutually coupled in a totem-pole configuration.