High frequency CMOS clock recovery circuit

• US 6,121,804 A
• Filed: 08/27/1998
• Issued: 09/19/2000
• Est. Priority Date: 08/27/1998
• Status: Expired due to Term

• Current Assignee: MACOM Connectivity Solutions, LLC (MACOM Technology Solutions Holdings, Inc.)
• Original Assignee: Applied Micro Circuits Corporation (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Fu, Wei, Bryan, Thomas Clark, Merrill, Allen Carl
• Primary Examiner(s): ZWEIZIG, JEFFERY SHAWN
• Application Number:
  US09/140,840
• Time in Patent Office: 754 Days
• Field of Search: 327/144, 327/155, 327/165, 327/166, 327/172, 327/176, 327/291, 327/292, 327/293, 327/294, 327/299
• US Class Current: 327/144
• CPC Class Codes: H03D 13/003 in which both oscillations are converted by logic means into pulses which are applied to filtering or integrating means
• CPC Class Codes: H03L 7/089 the phase or frequency detector generating up-down pulses H03L7/087 takes precedence
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Abstract

A complementary metal-oxide semiconductor (CMOS) integrated circuit that includes a clock recovery circuit. The clock recovery circuit automatically properly aligns a clock with data. A latch is used to perform the function of a flip-flop. Because the flip flop is essentially two latches, using the latch rather than the flip flop results in a circuit having one less latch. Consequently, the circuit has less propagation delay, which permits higher frequency operation. Use of the latch also reduces the load on the clock and saves power. Additionally, the clock recovery circuit uses differential logic, which decreases noise sensitivity and allows higher frequency operation.

Claims

1. A complementary metal-oxide semiconductor (CMOS) clock recovery circuit for synchronizing a clock with data, comprising:

a master-slave flip-flop having a clock input, a non-clock input, a data input, and an output;

a latch having a data input, a clock input, a non-clock input, and an output, the output of the master-slave flip-flop being connected to the data input of the latch;

a first exclusive-or gate having a first input, a second input, and an output, the data being connected to the first input and the output of the master-slave flip flop being connected to the second input;

a second exclusive-or gate having a first input, a second input, and an output, the output of the master-slave flip flop being connected to the first input and the output of the latch being connected to the second input;

means connected to the output of the first exclusive-or gate and connected to the output of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of the output of the first exclusive-or gate and the average voltage of the output of the second exclusive-or gate; and

a clock having an input connected to the output of the difference signal producing means, and clock and non-clock outputs connected, respectively, to the clock and non-clock inputs of the master-slave flip flop, wherein the non-clock output is the inversion of the clock output.

2. The CMOS clock recovery circuit of claim 1 wherein the master-slave flip flop has a pair of differential inputs, and wherein the output of the master-slave flip flop is a pair of differential outputs, the data input to the latch is a pair of differential data inputs, the output of the latch is a pair of differential outputs, the first input of the first exclusive-or gate is a first pair of differential inputs and the second input of the first exclusive-or gate is a second pair of differential inputs, the first input of the second exclusive-or gate is a first pair of differential inputs and the second input of the second exclusive-or gate is a second pair of differential inputs, and wherein the differential outputs of the master-slave flip flop are connected to the differential data inputs of the latch and to the second differential inputs of the first exclusive-or gate and to the first differential inputs of the second exclusive-or gate, and wherein the differential outputs of the latch are connected to the second differential inputs of the second exclusive-or gate, and wherein the data is a differential data pair that is connected to the differential inputs of the master-slave flip flop and to the first differential inputs of the first exclusive-or gate.

3. The CMOS clock recovery circuit of claim 1 wherein the difference signal producing means is an operational amplifier connected to the output of the first exclusive-or gate and connected to the output of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of the output of the first exclusive-or gate and the average voltage of the output of the second exclusive-or gate.

4. The CMOS clock recovery circuit of claim 1 wherein the first exclusive-or gate output is a pair of differential outputs and wherein the second exclusive-or gate output is a pair of differential outputs, and wherein the difference signal producing means is an operational amplifier connected to the differential outputs of the first exclusive-or gate and connected to the differential outputs of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of a first one of the differential outputs of the first exclusive-or gate and the average voltage of a first one of the differential outputs of the second exclusive-or gate and also representative of the difference between the average voltage of a second one of the differential outputs of the first exclusive-or gate and the average voltage of a second one of the differential outputs of the second exclusive-or gate.

5. The CMOS clock recovery circuit of claim 3 wherein the clock is a voltage controlled oscillator (VCO) having an input and an output, and wherein the difference signal is connected to the input of the VCO.

6. The CMOS clock recovery circuit of claim 1 wherein the master-slave flip flop has a pair of differential clock inputs and the latch has a pair of differential clock inputs, and wherein the clock is a differential clock pair connected to the differential clock inputs of the master-slave flip flop, and wherein the differential clock pair is invertedly connected to the differential clock inputs of the latch.

7. The CMOS clock recovery circuit of claim 1 wherein the master-slave flip flop, the latch, the first exclusive-or gate, and the second exclusive-or gate each have a VSS connector and a VDD connector, and wherein a voltage vdd is applied to the VDD connectors, and wherein a voltage vss is applied to the VSS connectors, wherein the difference between the voltage vdd and the voltage vss is about 3.3 volts for a 0.35 micron process.

8. The CMOS clock recovery circuit of claim 1 wherein the frequency of the clock is about 2.7 gigahertz for a 0.35 micron process.

9. A monolithic complementary metal-oxide semiconductor (CMOS) integrated circuit (IC), comprising:

one or more circuits, at least one of the circuits comprising a CMOS clock recovery circuit, the CMOS clock recovery circuit including;

a master-slave flip-flop having a data input, a clock input, a non-clock input, and an output;

a latch having a data input, a clock input, a non-clock input, and an output, the output of the master-slave flip flop being connected to the data input of the latch;

a first exclusive-or gate having a first input, a second input, and an output, the data being connected to the first input and the output of the master-slave flip flop being connected to the second input;

a second exclusive-or gate having a first input, a second input, and an output, the output of the master-slave flip flop being connected to the first input and the output of the latch being connected to the second input;

means connected to the output of the first exclusive-or gate and connected to the output of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of the output of the first exclusive-or gate and the average voltage of the output of the second exclusive-or gate; and

a clock having an input connected to the difference signal producing means, and clock and non-clock outputs connected, respectively, to the clock and non-clock inputs of the master-slave flip flop, wherein the non-clock output is the inversion of the clock output.

10. The IC device of claim 9 wherein the master-slave flip flop has a pair of differential inputs, and wherein the output of the master-slave flip flop is a pair of differential outputs, the data input to the latch is a pair of differential data inputs, the output of the latch is a pair of differential outputs, the first input of the first exclusive-or gate is a first pair of differential inputs and the second input of the first exclusive-or gate is a second pair of differential inputs, the first input of the second exclusive-or gate is a first pair of differential inputs and the second input of the second exclusive-or gate is a second pair of differential inputs, and wherein the differential outputs of the master-slave flip flop are connected to the differential data inputs of the latch and to the second differential inputs of the first exclusive-or gate and to the first differential inputs of the second exclusive-or gate, and wherein the differential outputs of the latch are connected to the second differential inputs of the second exclusive-or gate, and wherein the data is a differential data pair that is connected to the differential inputs of the master-slave flip flop and to the first differential inputs of the first exclusive-or gate.

11. The IC device of claim 9 wherein the the difference signal producing means is an operational amplifier connected to the output of the first exclusive-or gate and connected to the output of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of the output of the first exclusive-or gate and the average voltage of the output of the second exclusive-or gate.

12. The IC device of claim 9 wherein the first exclusive-or gate output is a pair of differential outputs and wherein the second exclusive-or gate output is a pair of differential outputs, and wherein the difference signal producing means is an operational amplifier connected to the differential outputs of the first exclusive-or gate and connected to the differential outputs of the second exclusive-or gate for producing a difference signal representative of the difference between the average voltage of a first one of the differential outputs of the first exclusive-or gate and the average voltage of a first one of the differential outputs of the second exclusive-or gate and also representative of the difference between the average voltage of a second one of the differential outputs of the first exclusive-or gate and the average voltage of a second one of the differential outputs of the second exclusive-or gate.

13. The IC device of claim 11 wherein the clock is a voltage controlled oscillator (VCO) having an input and an output, and wherein the difference signal is connected to the input of the VCO.

14. The IC device of claim 9 wherein the master-slave flip flop has a pair of differential clock inputs and the latch has a pair of differential clock inputs, and wherein the clock is a differential clock pair connected to the differential clock inputs of the master-slave flip flop, and wherein the differential clock pair is invertedly connected to the differential clock inputs of the latch.

15. The IC device of claim 9 wherein the master-slave flip flop, the latch, the first exclusive-or gate, and the second exclusive-or gate each have a VSS connector and a VDD connector, and wherein a voltage vdd is applied to the VDD connectors, and wherein a voltage vss is applied to the VSS connectors, wherein the difference between the voltage vdd and the voltage vss is about 3.3 volts for a 0.35 micron process.

16. The IC device of claim 9 wherein the frequency of the clock is about 2.7 gigahertz for a 35 micron process.