MOSFET substrate current logic

• US 5,939,899 A
• Filed: 04/23/1997
• Issued: 08/17/1999
• Est. Priority Date: 04/23/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Frommer, Aviv, Pinto, Mark R.
• Primary Examiner(s): Tokar, Michael
• Assistant Examiner(s): Chang, Daniel D.
• Application Number:
  US08/842,123
• Time in Patent Office: 846 Days
• Field of Search: 326/121, 326/119, 326/112, 326/52, 326/53, 326/54, 326/55, 326/49, 326/50, 326/21
• US Class Current: 326/119
• CPC Class Codes: H03K 19/0944 using MOSFET or insulated gate field-effect transistors, i.e. IGFETH03K19/096 takes precedence

Abstract

Logic devices of the present invention have one or more MOSFETs that are configured to operate in logic circuits, where voltages applied to the source and drain of each MOSFET are treated as logic inputs to the circuit and the resulting substrate current is treated as the logic output of the circuit. In one implementation, a MOSFET is configured in a circuit to operate as an XOR gate where a load resistor between the substrate and ground converts the substrate current into an output voltage. A sample-and-hold circuit samples and holds the output voltage to isolate the XOR gate thereby allowing DC power dissipation to be reduced. In another implementation, three MOSFETs are configured to operate as an "ORNAND" logic device that performs the logical addition of the OR function and the NAND function.

Claims

1. A logic device comprising one or more MOSFETs configured such that each channel input of each MOSFET is a logic input to the logic device and the substrate current of the one or more MOSFETs is a logic output of the logic device, wherein, for logic devices comprising two or more MOSFETs, the substrates of the two or more MOSFETs are interconnected and at least one channel node of each MOSFET is connected to a channel node of at least one other MOSFET to form a logic input to the logic device.

2. The invention of claim 1, comprising one MOSFET, wherein:

one of the channel contacts of the MOSFET is adapted to receive a first logic input; and

the other channel contact of the MOSFET is adapted to receive a second logic input.

3. The invention of claim 2, further comprising a load attached to the substrate of the MOSFET, wherein the load is adapted to convert the substrate current into an output voltage corresponding to the logic output of the logic device.

4. The invention of claim 3, wherein the logic device is adapted to operate as an XOR device.

5. The invention of claim 3, further comprising a sample-and-hold circuit connected to the load and adapted to sample and hold the output voltage.

6. The invention of claim 5, wherein the sample-and-hold circuit comprises a pass transistor connected at one channel input to the substrate of the MOSFET and a capacitor connected to the other channel input of the pass transistor, wherein, when the pass transistor is on, the capacitor samples the output voltage, and, when the pass transistor is off, the capacitor holds the sampled output voltage.

7. The invention of claim 1, comprising three MOSFETs, wherein:

the substrates of the three MOSFETs are interconnected;

one of the two channel contacts of the first MOSFET is connected to one of the two channel contacts of the second MOSFET and is adapted to receive a first logic input;

the other channel contact of the second MOSFET is connected to one of the two channel contacts of the third MOSFET and is adapted to receive a second logic input; and

the other channel contact of the first MOSFET and the other channel contact of the third MOSFET are adapted to receive a third logic input.

8. The invention of claim 7, further comprising a load attached to the substrates of the three MOSFETs, wherein the load is adapted to convert the substrate current into an output voltage corresponding to the logic output of the logic device.

9. The invention of claim 8, wherein the logic device is adapted to operate as an ORNAND device.

10. The invention of claim 8, further comprising a sample-and-hold circuit connected to the load and adapted to sample and hold the output voltage.

11. The invention of claim 10, wherein the sample-and-hold circuit comprises a pass transistor connected at one channel input to the substrates of the three MOSFETs and a capacitor connected to the other channel input of the pass transistor, wherein, when the pass transistor is on, the capacitor samples the output voltage, and, when the pass transistor is off, the capacitor holds the sampled output voltage.

12. The invention of claim 7, wherein the channel contacts connecting the first and second MOSFETs are a single merged junction and the channel contacts connecting the second and third MOSFETs are another single merged junction.

13. The invention of claim 1, further comprising:

a load attached to the substrates of the one or more MOSFETs, wherein the load is adapted to convert the substrate current into an output voltage corresponding to the logic output of the logic device; and

a sample-and-hold circuit connected to the load and adapted to sample and hold the output voltage.

14. The invention of claim 13, wherein the sample-and-hold circuit comprises a pass transistor connected at one channel input to the substrates of the one or more MOSFETs and a capacitor connected to the other channel input of the pass transistor, wherein, when the pass transistor is on, the capacitor samples the output voltage, and, when the pass transistor is off, the capacitor holds the sampled output voltage.

15. The invention of claim 1, comprising two or more MOSFETs, wherein each of one or more pairs of the MOSFETs share a single merged junction.

16. A method for operating a logic device comprising one or more MOSFETs, comprising the steps of:

(a) applying two or more logic inputs to the two or more channel contacts of the one or more MOSFETs; and

(b) treating the substrate current of the one or more MOSFETs as a logic output of the logic device, wherein, for logic devices comprising two or more MOSFETs, the substrates of the two or more MOSFETs are interconnected and at least one channel node of each MOSFET is connected to a channel node of at least one other MOSFET to form a logic input to the logic device.

17. The invention of claim 16, wherein step (b) comprises the step of converting the substrate current into an output voltage.

18. The invention of claim 17, wherein step (b) further comprises the steps of sampling and holding the output voltage.

19. The invention of claim 16, wherein:

the logic device comprises one MOSFET;

step (a) comprises the step of applying two logic inputs to the channel contacts of the MOSFET; and

step (b) comprises the step of treating the substrate current as an XOR output of the logic device.

20. The invention of claim 16, wherein:

the logic device comprises three MOSFETs, wherein;

the substrates of the three MOSFETs are interconnected;

one of the two channel contacts of the first MOSFET is connected to one of the two channel contacts of the second MOSFET and is adapted to receive a first logic input;

the other channel contact of the second MOSFET is connected to one of the two channel contacts of the third MOSFET and is adapted to receive a second logic input; and

the other channel contact of the first MOSFET and the other channel contact of the third MOSFET are adapted to receive a third logic input;

step (a) comprises the step of applying three logic inputs to the channel contacts of the three MOSFETs; and

step (b) comprises the step of treating the substrate current as an ORNAND output of the logic device.

21. The invention of claim 20, wherein the channel contacts connecting the first and second MOSFETs are a single merged junction and the channel contacts connecting the second and third MOSFETs are another single merged junction.

22. The invention of claim 16, comprising two or more MOSFETs, wherein each of one or more pairs of the MOSFETs share a single merged junction.