CMOS to ECL translator with incorporated latch

• US 5,214,317 A
• Filed: 05/04/1992
• Issued: 05/25/1993
• Est. Priority Date: 05/04/1992
• 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): Sikes, William L.
• Assistant Examiner(s): CUNNINGHAM, TERRY D
• Application Number:
  US07/878,134
• Time in Patent Office: 386 Days
• Field of Search: 307/272.1, 307/279, 307/289, 307/290, 307/291, 307/355, 307/446, 307/448, 307/455, 307/475, 307/530, 307/570
• US Class Current: 326/66
• CPC Class Codes: H03K 3/2885 the input circuit having a differential configuration
• CPC Class Codes: H03K 3/356034 the input circuit having a differential configuration

Abstract

An electrical circuit is disclosed which implements a CMOS to ECL translator with an incorporated latch. The invention provides a circuit which uses a small number of devices, and provides fast transition times with low power consumption.

Claims

1. A latch circuit comprising:

a first MOS transistor having a first terminal coupled to a first output node, a gate terminal coupled to a first latch input for performing a set function on said latch circuit, and a second terminal coupled to a first node;

a second MOS transistor having a first terminal coupled to a second output node, a gate terminal coupled to a second latch input for performing a reset function on said latch circuit, and a second terminal coupled to said first node;

a third MOS transistor having a first terminal coupled to said first output node, a second terminal coupled to said first node and a gate coupled to said second output node;

a fourth MOS transistor having a first terminal coupled to said second output node, a second terminal coupled to said first node and a gate coupled to said first output node;

a first resistor having a first terminal coupled to said first output node and a second terminal coupled to a first voltage;

a second resistor having a first terminal coupled to said second output terminal and a second terminal coupled to said first voltage;

a constant current source coupled between said first node and a second voltage; and

where said first and second latch inputs operate in a first voltage range and where said first and second output nodes operate in a second voltage range.

2. The latch circuit of claim 1, further comprising

voltage drop means coupled between said first voltage and first and second resistors for causing a constant voltage drop between said first voltage and said second terminals of said resistors.

3. The latch circuit of claim 2, wherein said constant voltage drop is about 0.7 volts.

4. The latch circuit of claim 3, wherein said voltage drop means is one of a diode or transistor configured as a diode.

5. The latch circuit of claim 1 wherein said first voltage is approximately equal to 5 volts.

6. The latch circuit of claim 1 wherein said second voltage is approximately equal to zero volts.

7. The latch circuit of claim 1, wherein said second voltage range has a voltage differential from a maximum voltage to a minimum voltage of about 0.8 volts.