Multiple input CMOS logic circuits

• US 5,045,723 A
• Filed: 07/31/1990
• Issued: 09/03/1991
• Est. Priority Date: 07/31/1990
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Mao, Robert S.
• Primary Examiner(s): Hudspeth, David
• Assistant Examiner(s): OUELLETTE, SCOTT
• Application Number:
  US07/560,381
• Time in Patent Office: 399 Days
• Field of Search: 307/451, 307/443, 307/448, 307/449, 307/272.2, 307/279, 307/291
• US Class Current: 326/121
• CPC Class Codes: H03K 19/0948 using CMOS or complementary insulated gate field-effect transistors
• CPC Class Codes: H03K 19/1738 using cascode switch logic [CSL] or cascode emitter coupled logic [CECL]

Abstract

A multiple input CMOS logic circuit includes a bistable input section with two nodes. In an inactive state, the input section maintains the nodes at opposite CMOS logic levels. In an active state, the nodes are maintained at substantially equal levels positioned between the two CMOS logic levels. The input circuit includes a set of parallel CMOS transistor pairs, cross connected at the nodes. The CMOS pairs are unbalanced by inequality of transistor gate widths. The imbalance causes the input circuit to assume the inactive state. A plurality of input CMOS transistors are connected in parallel between the nodes and receive input signals at their gates. When any of the input transistors is turned on by a change of input signal state, it conducts between the nodes, causing the input circuit to transition to the active state. An output buffer connected to the nodes translates the node levels to CMOS signal levels.

Claims

1. A multiple input MOS logic circuit, including:

a complementary MOS output buffer having a first translation connection, a second translation connection, and an output connection and providing at said output connection a MOS logic signal in response to respective first and second level signals at said first and second translation connections, said MOS logic signal having a first state when said first and second level signals are substantially unequal and a second state when said first and second level signals are substantially equal;

a bistable CMOS input circuit having a first multi-contact connection point coupled to said first translation connection and a second multi-contact connection point coupled to said second translation connection, said bistable CMOS input circuit providing substantially unequal level signals at said first and second multi-contact connection points in response to a first state of conductivity between said first and second multi-contact connection points, and providing substantially equal level signals at said first and second multi-contact connection points in response to a second state of conductivity between said first and second multi-contact connection points; and

a plurality of input CMOS transistor circuits, each having a first current conducting terminal connected to said first multi-contact connection point, a second current conduction terminal connected to said second multi-contact connection point, and at least one gate terminal for establishing said first or said second state of conductivity between said first and second current conducting terminals in response to the state of one of a plurality of CMOS signals input to said circuit.

2. The multiple input MOS logic circuit of claim 1, wherein the bistable CMOS input circuit includes:

a first CMOS load transistor with a drain for connection to a drain potential, a source connected to the first multi-contact node, and a gate connected to the second multi-contact node;

a first CMOS driver transistor with a drain connected to the first multi-contact node, a source for connection to a source potential, and a gate connected to the second multi-contact node;

a second CMOS load transistor with a drain for connection to said drain potential, a source connected to the second multi-contact node, and a gate connected to the first multi-contact node; and

a second CMOS driver transistor with a drain connected to the second multi-contact node, a source for connection to a source potential, and a gate connected to the first multi-contact node;

and, wherein the gate of the first CMOS load transistor is wider than the gate of the second CMOS load transistor; and

the gate of the second CMOS driver transistor is wider than the gate of the first CMOS driver transistor.

3. The multiple input MOS logic circuit of claim 1, wherein the first state of conductivity is established by all of the input CMOS transistors being off.

4. The multiple input MOS logic circuit of claim 3, wherein the second state of conductivity is established by any of the input CMOS transistors being on.

5. A CMOS logic circuit, comprising:

first and second multi-contact nodes;

a plurality of CMOS input transistors connected in parallel between the first and second multi-contact nodes, each of the CMOS input transistors having a gate for switching the transistor to an on state in response to a predetermined CMOS logic signal level;

a unbalanced, bistable CMOS input circuit coupled to the first and second multi-contact nodes, the unbalanced, bistable CMOS input circuit having a quiescent state in which it provides a voltage at the first multi-contact node at a level substantially equal to a CMOS logic high level and a voltage at the second multi-contact node at a level substantially equal to a CMOS logic low level, and said unbalanced, bistable input CMOS circuit responding to the on state of any input transistor by switching to an active state and changing the voltages to substantially equal levels between the CMOS logic high and low levels; and

an output buffer coupled to the first and second multi-contact nodes for providing an output signal conditioned to a predetermined CMOS logic level by the voltages at the first and second nodes.

6. The CMOS logic circuit of claim 5, wherein the unbalanced, bistable CMOS input circuit includes:

a first CMOS load transistor with a drain for connection to a drain potential, a source connected to the first multi-contact node, and a gate connected to the second multi-contact node;

a first CMOS driver transistor with a drain connected to the first multi-contact node, a source for connection to a source potential, and a gate connected to the second multi-contact node;

a second CMOS load transistor with a drain for connection to said drain potential, a source connected to the second multi-contact node, and a gate connected to the first multi-contact node; and

a second CMOS driver transistor with a drain connected to the second multi-contact node, a source for connection to a source potential, and a gate connected to the first multi-contact node;

and, wherein the gate of the first CMOS load transistor is wider than the gate of the second CMOS load transistor; and

the gate of the second CMOS driver transistor is wider than the gate of the first CMOS driver transistor.

7. A CMOS logic circuit, comprising:

a plurality of substantially identical input CMOS transistors, each including drain and source connections and a gate connection for receiving a respective one of a plurality of input logic signals;

a first node connected to the drain of each input transistor and a second node connected to the source of each input transistor;

a CMOS input circuit including a first CMOS load transistor with a drain for connection to a drain potential, a source connected to the first node and a gate connected to the second node, a first CMOS drive transistor with a drain connected to the first node, a source for connection to a source potential, and a gate connected to the second node, a second CMOS load transistor with a drain for connection to the drain potential, a source connected to the second node, and a gate connected to the first node, and a second CMOS driver transistor with a drain connected to the second node, a source for connection to the source potential, and a gate connected to the first node, wherein the gate of the first CMOS load transistor is wider than the gate of the second CMOS load transistor and the gate of the second CMOS driver transistor is wider than the gate of the first CMOS driver transistor; and

a complementary MOS output buffer with a first translation connection coupled to the first node, a second translation connection coupled to the second node, and an output connection, the output buffer providing at said output connection a MOS logic signal in response to respective first and second level signals at the first and second nodes, the logic signal having a first state when the first and second level signals are substantially unequal and a second state when the first and second level signals are substantially equal.