SYSTEM AND METHOD FOR LEVEL-SHIFTING VOLTAGE SIGNALS USING A DYNAMIC LEVEL-SHIFTING ARCHITECTURE

• US 20120280739A1
• Filed: 05/02/2011
• Published: 11/08/2012
• Est. Priority Date: 05/02/2011
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Foley, David
• Granted Patent: US 8,659,341 B2
• Time in Patent Office: Days
• US Class Current: 327/333
• CPC Class Codes: H03K 3/356165 using additional transistors in the feedback circuit

Abstract

A system and method to level-shift multiple signals from a first voltage domain to a second voltage domain with minimized silicon area. A level-shifting system may be organized by implementing a static level-shifter coupled to a plurality of dynamic level-shifters. The static level-shifter may provide a voltage control signal for each of the dynamic level-shifters. Each of the dynamic level-shifters may level-shift an individual input signal from a first voltage domain to a second voltage domain.

Claims

1. A voltage shifting data transmission system, comprising:

a static level-shifter having an input for a control signal within a first voltage domain and an output for a signal representing the strobe signal shifted to a second voltage domain; and

a plurality of dynamic level-shifters, each having a first input coupled to the shifted strobe signal, a second input for a respective data signal within the first voltage domain, and an output for a signal representing the respective data signal shifted to the second voltage domain.

2. The system of claim 1, wherein the dynamic level-shifters are characterized by a reset phase and an active phase, the dynamic level-shifters outputting the shifted data signals during the active phase.

3. The system of claim 1, further comprising an activity detector coupled to the data signals of the first voltage domain to block transition of the shifted strobe signal from the static level-shifter in when the data signals are static.

4. The system of claim 1, wherein the static level shifter comprises:

a first stage of cross-coupled transistor circuit paths extending between a supply of the first voltage domain and a supply of the second voltage domain, each path including a transistor that is coupled to one of a differential pair of strobe signal, and

a second stage of cross-coupled transistor circuit paths extending between supplies of the second voltage domain, each path including a transistor that is coupled to a respective one of the circuit paths of the first stage.

5. The system of claim 1, wherein the static level shifter comprises:

a first stage of cross-coupled transistor circuit paths extending between a supply of the first voltage domain and a supply of the second voltage domain, each path including a transistor that is coupled to one of a differential pair of strobe signal,

an inverter, having an input coupled to a first circuit path from the first stage, and

a second stage of cross-coupled transistor circuit paths extending between supplies of the second voltage domain, a first path including a transistor that is coupled to an output of the inverter and a second path including a transistor that is coupled to a second path of the first stage.

6. The system of claim 1, wherein at least one dynamic level shifter comprises a first pair of cross-coupled circuit paths extending between supplies of the second voltage domain, each circuit path including:

a data transistor having an input for one of a differential pair of data signals in the first voltage domain,

a pair of transistors connected as an inverter and having inputs coupled to an intermediate node of the other circuit path,

a first control transistor having a source to drain path extending between a first supply and the intermediate node of the circuit path and having an input coupled to the shifted strobe signal, and

a second control transistor having a source to drain path extending between a second supply and the data transistor and having an input coupled to the shifted strobe signal.

7. The system of claim 1, wherein at least one dynamic level shifter comprises

a first pair of cross-coupled circuit paths extending between supplies of the second voltage domain, each circuit path including:

a data transistor having an input for one of a differential pair of data signals in the first voltage domain,

a pair of transistors connected as an inverter and having inputs coupled to an intermediate node of the other circuit path, and

a first control transistor having a source to drain path extending between a first supply and the intermediate node of the circuit path and having an input coupled to the shifted strobe signal; and

another control transistor having a source to drain path extending between a second supply and the data transistors of both circuit paths and having an input coupled to the shifted strobe signal.

8. The system of claim 1, wherein outputs of the dynamic level shifters are directly coupled to output pins of an integrated circuit.

9. A circuit system, comprising:

a first integrated circuit having inputs for a plurality of control signals, the inputs operable in a first voltage domain,

a second integrated circuit having outputs coupled to the control inputs of the first integrated circuit and having internal processing logic operable in a second voltage domain, the second integrated circuit having an output system that comprises;

a static level-shifter having an input for a control signal within the second voltage domain and an output for a signal representing the strobe signal shifted to the first voltage domain; and

a plurality of dynamic level-shifters, each having a first input coupled to the shifted strobe signal, a second input for a respective data signal within the second voltage domain, and an output for a signal representing the respective data signal shifted to the first voltage domain.

10. The system of claim 9, wherein the static level shifter comprises:

a first stage of cross-coupled transistor circuit paths extending between a supply of the second voltage domain and a supply of the first voltage domain, each path including a transistor that is coupled to one of a differential pair of strobe signal, and

a second stage of cross-coupled transistor circuit paths extending between supplies of the first voltage domain, each path including a transistor that is coupled to a respective one of the circuit paths of the first stage.

11. The system of claim 9, wherein the static level shifter comprises:

a first stage of cross-coupled transistor circuit paths extending between a supply of the second voltage domain and a supply of the first voltage domain, each path including a transistor that is coupled to one of a differential pair of strobe signal,

an inverter, having an input coupled to a first circuit path from the first stage, and

a second stage of cross-coupled transistor circuit paths extending between supplies of the first voltage domain, a first path including a transistor that is coupled to an output of the inverter and a second path including a transistor that is coupled to a second path of the first stage.

12. The system of claim 9, wherein at least one dynamic level shifter comprises a first pair of cross-coupled circuit paths extending between supplies of the first voltage domain, each circuit path including:

a data transistor having an input for one of a differential pair of data signals in the first voltage domain;

a pair of transistors connected as an inverter and having inputs coupled to an intermediate node of the other circuit path,

a first control transistor having a source to drain path extending between a first supply and the intermediate node of the circuit path and having an input coupled to the shifted strobe signal, and

a second control transistor having a source to drain path extending between a second supply and the data transistor and having an input coupled to the shifted strobe signal.

13. The system of claim 9, wherein at least one dynamic level shifter comprises

a first pair of cross-coupled circuit paths extending between supplies of the first voltage domain, each circuit path including:

a data transistor having an input for one of a differential pair of data signals in the first voltage domain;

a pair of transistors connected as an inverter and having inputs coupled to an intermediate node of the other circuit path, and

a first control transistor having a source to drain path extending between a first supply and the intermediate node of the circuit path and having an input coupled to the shifted strobe signal; and

another control transistor having a source to drain path extending between a second supply and the data transistors of both circuit paths and having an input coupled to the shifted strobe signal.

14. The system of claim 9, wherein outputs of the dynamic level shifters are directly coupled to output pins of the second integrated circuit.

15. A method of converting data signals from a first voltage domain to a second voltage domain, comprising:

shifting a control strobe from the first voltage domain to the second voltage domain,

during a reset period of the control strobe, resetting a plurality of dynamic level shifters, and

during an active period of the control strobe, shifting data signals input to the dynamic levels shifters from the first voltage domain to the second voltage domain.

16. The method of claim 15, wherein the shifting of the control strobe comprises shifting the strobe through a pair of stages:

a first stage shifting a first voltage limit of the input strobe from the first domain to the second voltage domain, and,

a second stage shifting a second voltage limit of the input strobe from the first domain to the second domain.

17. The method of claim 15, further comprising:

determining whether data signals input to the dynamic level shifters have changed between a first active period and a second active period, and

if the data signals have not changed, blocking propagation of a reset period of the control strobe.

18. A dynamic level-shifter circuit, comprising:

a first and second circuit path extending between a voltage domain source supply and drain supply,

a series of cross-coupled transistors situated along the respective first and second circuit path between the source supply and a respective first and second path intermediate node N₁ and N₂.

respective transistors for receiving a control voltage within the source and drain supply voltage range situated along the respective first and second circuit path between the source supply and the respective intermediate node N₁ and N₂,

respective transistors for receiving differential voltage inputs situated along the respective first and second circuit path between the respective first and second path intermediate node N₁ and N₂ and a third intermediate node N₃,

a transistor for receiving a control voltage within the source and drain supply voltage range situated between the drain supply and the intermediate node N3, and

differential outputs formed by respective inverters situated between the source supply and drain supply coupled to the respective first and second path intermediate node N₁ and N₂.