Low power high-speed output driver

• US 7,956,645 B2
• Filed: 03/17/2008
• Issued: 06/07/2011
• Est. Priority Date: 03/17/2008
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Momtaz, Afshin
• Primary Examiner(s): Cho; James H.
• Assistant Examiner(s): LO, CHRISTOPHER KWOK YEUNG
• Application Number:
  US12/049,701
• Publication Number:
  US 20090230993A1
• Time in Patent Office: 1,177 Days
• Field of Search: 326/83, 326 86- 87, 326/112, 326/115, 326/127, 326/26, 326/27, 326/33, 326/80, 326/81, 327/65, 327/362, 327108-112, 327/379, 327/389, 327/391, 327/333, 327/66, 327/67
• US Class Current: 326/86
• CPC Class Codes: H03K 19/017509 Interface arrangements

Abstract

Low power high-speed output driver. An array of switches (some of which are inverting switches whose connectivity is governed oppositely as the control signal provided to it) is implemented such that an input signal governs the connectivity of those switches. A resistor is coupled between the nodes interposed between the switches of the array, and an output signal is taken from the nodes at ends of the resistor. The high voltage level of such an output driver is truly the level of the power supply energizing the circuit (e.g., VDD) while still consuming relatively low power.

Claims

1. An apparatus, comprising:

an input implemented to receive a differential input signal that includes a first input signal and a second input signal;

first and second switches;

first and second inverting switches;

a constant current source such that a first end of the constant current source is grounded and a second end of the constant current source directly connects to a first end of the first switch and a first end of the second switch;

a resistor that directly connects between a second end of the first switch and a second end of the second switch; and

an output implemented to output a differential output signal that includes a first output signal and a second output signal; and

wherein;

the first input signal is provided to the second inverting switch and the second switch such that the first input signal ensures that the second inverting switch is closed when the second switch is open;

the second input signal is provided to the first inverting switch and the first switch such that the second input signal ensures that the first inverting switch is closed when the first switch is open;

a first end of the first inverting switch directly connects to a power supply and a second end of the first inverting switch directly connects to the second end of the first switch;

a first end of the second inverting switch directly connects to the power supply and a second end of the second inverting switch directly connects to the second end of the second switch

the first output signal, having a respective high voltage level being that of the power supply, is output from a first end of the resistor; and

the second output signal, having a respective high voltage level being that of the power supply, is output from a second end of the resistor.

2. The apparatus of claim 1, further comprising:

a first inverter, directly connected to the second inverting switch and the second switch, that inverts the first input signal before the first input signal is provided to the second inverting switch and the second switch; and

a second inverter, directly connected to the first inverting switch and the first switch, that inverts the second input signal before the second input signal is provided to the first inverting switch and the first switch.

3. The apparatus of claim 1, wherein:

the resistor is a 100Ω

resistor.

4. The apparatus of claim 1, further comprising:

a first capacitor that is coupled to the second end of the first switch; and

a second capacitor that is coupled to the second end of the second switch.

5. The apparatus of claim 1, wherein:

the resistor is a first resistor; and

further comprising;

a first capacitor that is coupled to the second end of the first switch;

a second capacitor that is coupled to the second end of the second switch;

a second resistor coupled between the first capacitor and the power supply; and

a third resistor coupled between the second capacitor and the power supply.

6. The apparatus of claim 1, wherein:

the resistor is a first resistor;

the apparatus is a first integrated circuit;

the first integrated circuit is coupled to a second integrated circuit that includes;

a first capacitor that is coupled to the second end of the first switch;

a second capacitor that is coupled to the second end of the second switch;

a second resistor coupled between the first capacitor and the power supply; and

a third resistor coupled between the second capacitor and the power supply.

7. The apparatus of claim 6, wherein:

the second resistor has an impedance of 50Ω

; and

the third resistor has an impedance of 50Ω

.

8. The apparatus of claim 1, further comprising:

a first inverter, directly connected to the second inverting switch and the second switch, that inverts the first signal before the first signal is provided to the second inverting switch and the second switch;

a second inverter, directly connected to the first inverting switch and the first switch, that inverts the second signal before the second signal is provided to the first inverting switch and the first switch;

a flip-flop having two inputs that are coupled to inputs of the first inverter and the second inverter, respectively;

third and fourth switches that are respectively governed by two outputs of the flip-flop;

at least one additional constant current source such that a first end of the at least one additional constant current source is grounded and a second end of the at least one additional constant current source directly connects to a first end of the third switch and a first end of the fourth switch; and

wherein;

a second end of the third switch is coupled to the second end of the first switch; and

a second end of the fourth switch is coupled to the second end of the second switch.

9. The apparatus of claim 1, further comprising:

a first inverter, directly connected to the second inverting switch and the second switch, that inverts the first signal before the first signal is provided to the second inverting switch and the second switch;

a second inverter, directly connected to the first inverting switch and the first switch, that inverts the second signal before the second signal is provided to the first inverting switch and the first switch;

a flip-flop having two inputs that are coupled to inputs of the first inverter and the second inverter, respectively;

third and fourth switches;

third and fourth inverting switches;

at least one additional constant current source such that a first end of the at least one additional constant current source is grounded and a second end of the at least one additional constant current source directly connects to a first end of the third switch and a first end of the fourth switch; and

wherein;

a first output signal from the flip-flop is provided to the fourth inverting switch and the fourth switch such that the first output signal from the flip-flop ensures that the fourth inverting switch is closed when the fourth switch is open;

a second output signal from the flip-flop is provided to the third inverting switch and the third switch such that the second output signal from the flip-flop ensures that the third inverting switch is closed when the third switch is open;

a second end of the third switch is coupled to the second end of the first switch; and

a second end of the fourth switch is coupled to the second end of the second switch.

10. The apparatus of claim 1, wherein:

at least one of the first switch, the second switch, the first inverting switch, and

the second inverting switch is implemented using an n-channel metal oxide semiconductor field-effect transistor (N-MOSFET), a p-channel metal oxide semiconductor field-effect transistor (P-MOSFET), or a transfer gate.

11. The apparatus of claim 1, wherein:

the apparatus is a circuitry that is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.

12. An apparatus, comprising:

a first inverter implemented to invert a first input signal of a differential input signal;

a second inverter implemented to invert a second input signal of the differential input signal;

first and second switches;

first and second inverting switches;

a constant current source such that a first end of the constant current source is grounded and a second end of the constant current source directly connects to a first end of the first switch and a first end of the second switch;

a resistor that directly connects a second end of the first switch and a second end of the second switch; and

an output implemented to output a differential output signal that includes a first output signal and a second output signal; and

wherein;

an output of the first inverter directly connects to the second inverting switch and the second switch such to ensure that the second inverting switch is closed when the second switch is open;

an output of the second inverter directly connects to the first inverting switch and the first switch to ensure that the first inverting switch is closed when the first switch is open;

the first output signal, having a respective high voltage level being that of a power supply, is output from a first end of the resistor;

the second output signal, having a respective high voltage level being that of the power supply, is output from a second end of the resistor;

a first end of the first inverting switch directly connects to the power supply and a second end of the first inverting switch directly connects to the second end of the first switch; and

a first end of the second inverting switch directly connects to the power supply and a second end of the second inverting switch directly connects to the second end of the second switch.

13. The apparatus of claim 12, further comprising:

a flip-flop having two inputs that are coupled to inputs of the first inverter and the second inverter, respectively;

third and fourth switches that are respectively governed by two outputs of the flip-flop;

at least one additional constant current source such that a first end of the at least one additional constant current source is grounded and a second end of the at least one additional constant current source directly connects to a first end of the third switch and a first end of the fourth switch; and

wherein;

at least one additional current source coupled between ground and a node that couples a first end of the third switch and a first end of the second switch; and

wherein;

a second end of the third switch is coupled to the second end of the first switch; and

a second end of the fourth switch is coupled to the second end of the second switch.

14. The apparatus of claim 12, further comprising:

a flip-flop having two inputs that are coupled to inputs of the first inverter and the second inverter, respectively;

third and fourth switches;

third and fourth inverting switches;

at least one additional constant current source such that a first end of the at least one additional constant current source is grounded and a second end of the at least one additional constant current source directly connects to a first end of the third switch and a first end of the fourth switch; and

wherein;

a first output signal from the flip-flop is provided to the fourth inverting switch and the fourth switch such that the first output signal from the flip-flop ensures that the fourth inverting switch is closed when the fourth switch is open;

a second output signal from the flip-flop is provided to the third inverting switch and the third switch such that the second output signal from the flip-flop ensures that the third inverting switch is closed when the third switch is open;

a second end of the third switch is coupled to the second end of the first switch; and

a second end of the fourth switch is coupled to the second end of the second switch.

15. The apparatus of claim 12, wherein:

at least one of the first switch, the second switch, the first inverting switch, and the second inverting switch is implemented using an n-channel metal oxide semiconductor field-effect transistor (N-MOSFET), a p-channel metal oxide semiconductor field-effect transistor (P-MOSFET), or a transfer gate.

16. The apparatus of claim 12, wherein:

the apparatus is a circuitry that is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.

17. An apparatus, comprising:

a first inverter implemented to invert a first input signal of a differential input signal;

a second inverter implemented to invert a second input signal of the differential input signal;

a flip-flop having two inputs that are coupled to inputs of the first inverter and the second inverter, respectively;

first and second switches;

first and second inverting switches;

third and fourth switches that are respectively governed by two outputs of the flip-flop;

a first constant current source such that a first end of the first constant current source is grounded and a second end of the first constant current source directly connects to a first end of the first switch and a first end of the second switch;

a second constant current source such that a first end of the second constant current source is grounded and a second end of the second constant current source directly connects to a first end of the third switch and a first end of the fourth switch;

a resistor that directly connects between a second end of the first switch and a second end of the second switch; and

an output implemented to output a differential output signal that includes a first output signal and a second output signal; and

wherein;

an output of the first inverter couples to the second inverting switch and the second switch such to ensure that the second inverting switch is closed when the second switch is open;

an output of the second inverter couples to the first inverting switch and the first switch to ensure that the first inverting switch is closed when the first switch is open;

the first output signal, having a respective high voltage level being that of a power supply, is output from a first end of the resistor;

the second output signal, having a respective high voltage level being that of the power supply, is output from a second end of the resistor;

a first end of the first inverting switch directly connects to a the power supply and a second end of the first inverting switch connects to the second end of the first switch;

a first end of the second inverting switch directly connects to the power supply and a second end of the second inverting switch connects to the second end of the second switch;

a second end of the third switch is coupled to the second end of the first switch; and

a second end of the fourth switch is coupled to the second end of the second switch.

18. The apparatus of claim 17, wherein:

the resistor is a first resistor; and

further comprising;

a first capacitor that is coupled to the second end of the first switch;

a second capacitor that is coupled to the second end of the second switch;

a second resistor coupled between the first capacitor and the power supply; and

a third resistor coupled between the second capacitor and the power supply.

19. The apparatus of claim 17, wherein:

at least one of the first switch, the second switch, the first inverting switch, and the second inverting switch is implemented using an n-channel metal oxide semiconductor field-effect transistor (N-MOSFET), a p-channel metal oxide semiconductor field-effect transistor (P-MOSFET), or a transfer gate.

20. The apparatus of claim 17, wherein:

the apparatus is a circuitry that is implemented within a communication device; and

the communication device is implemented within at least one of a satellite communication system, a wireless communication system, a wired communication system, and a fiber-optic communication system.