Methods and apparatus for adjusting the deadtime between non-overlapping clock signals

• US 6,310,499 B1
• Filed: 07/17/2000
• Issued: 10/30/2001
• Est. Priority Date: 07/17/2000
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Radjassamy, Rajakrishnan
• Primary Examiner(s): TON, MY TRANG
• Application Number:
  US09/617,373
• Time in Patent Office: 470 Days
• Field of Search: 327/153, 327/155, 327/161, 327/166, 327/170, 327/172-176, 327/225, 327/259, 327/263, 327/239, 327/276, 327/291-294, 327/298, 327/299
• US Class Current: 327/175
• CPC Class Codes: G06F 1/06 Clock generators producing several clock signals G06F1/08 - G06F1/14 take precedence
• CPC Class Codes: H03K 5/1515 non-overlapping

Abstract

A clock gater circuit which may be easily tuned for the purpose of adjusting the deadtime between non-overlapping clock signals. The clock gater circuit has first and second clock inputs, a clock output, a falling clock edge generation circuit, and a rising clock edge generation circuit. The falling clock edge generation circuit is coupled between the first clock input and the clock output, and the rising clock edge generation circuit is coupled between the second clock input and the clock output. Each clock edge generation circuit has a feed-forward path and a feedback path. The feed-forward path of one of the clock edge generation circuits includes an inverter chain having an even number of inverters. If the inverter chain appears in the rising clock edge generation circuit, the inverter chain provides for easy adjustment of the rising edge of a clock produced by the gater circuit. However, an inverter chain which provides for easy adjustment of the timing of a clock edge may be provided in either or both of the clock edge generation circuits. When a clock gater circuit as described above is incorporated. into a system of clock gaters which produces a pair of non-overlapping clocks, the gater circuit can be used to easily adjust one or more deadtimes between the non-overlapping clocks.

Claims

1. A clock gater circuit, comprising:

a) first and second clock inputs;

b) a clock output;

c) a falling clock edge generation circuit coupled between the first clock input and the clock output, said falling clock edge generation circuit comprising a feed-forward path and a feedback path; and

d) a rising clock edge generation circuit coupled between the second clock input and the clock output, said rising clock edge generation circuit comprising a feed-forward path and a feedback path;

wherein the feed-forward path of one of the clock edge generation circuits comprises an even number more inverters than the feed-forward path of the other clock edge generation circuit.

2. A clock gater circuit as in claim 1, wherein:

a) the feedback path of the falling clock edge generation circuit is coupled to a first input of a logic gate, which logic gate forms a part of the feed-forward path of the falling clock edge generation circuit; and

b) the even number more inverters are coupled between the first clock input and the logic gate.

3. A clock gater circuit as in claim 1, wherein:

a) the feedback path of the rising clock edge generation circuit is coupled to a first input of a logic gate, which logic gate forms a part of the feed-forward path of the rising clock edge generation circuit; and

b) the even number more inverters are coupled between the second clock input and the logic gate.

4. A method for changing the duty cycle of a clock signal, comprising:

a) providing a clock gater circuit comprising first and second clock inputs;

a clock output;

a falling clock edge generation circuit coupled between the first clock input and the clock output, said falling clock edge generation circuit comprising a feed-forward path and a feedback path; and

a rising clock edge generation circuit coupled between the second clock input and the clock output, said rising clock edge generation circuit comprising a feed-forward path and a feedback path;

wherein the feed-forward path of one of the clock edge generation circuits comprises an even number more inverters than the feed-forward path of the other clock edge generation circuit;

b) sizing one or more of the inverters to thereby affect a change in the duty cycle of a clock signal produced at said clock output.

5. A method as in claim 4, wherein the even number more inverters is two.

6. A method as in claim 5, wherein sizing one or more of the inverters consists of sizing only one of the two inverters.

7. Circuitry for producing non-overlapping clocks with a desired deadtime, comprising:

a) a first clock gater circuit, comprising;

i) one or more inputs for receiving a clock signal; and

ii) an output for producing a first gated clock signal; and

b) a second clock gater circuit, comprising;

i) first and second inputs for receiving said clock signal;

ii) an output for producing a second gated clock signal;

iii) a falling clock edge generation circuit coupled between the first clock input and the clock output, said falling clock edge generation circuit comprising a feed-forward path and a feedback path; and

iv) a rising clock edge generation circuit coupled between the second clock input and the clock output, said rising clock edge generation circuit comprising a feed-forward path and a feedback path;

wherein the feed-forward path of one of the second clock gater circuit'"'"'s clock edge generation circuits comprises an even number more inverters than the feed-forward path of the second clock gater circuit'"'"'s other clock edge generation circuit, whereby adjustments in one or more of the inverters change a deadtime between the first and second gated clock signals.

8. Circuitry as in claim 7, wherein the even number more inverters lies in the feed-forward path of the rising clock edge generation circuit of the second clock gater circuit.

9. Circuitry as in claim 8, wherein the feed-forward path of the falling clock edge generation circuit of the second clock gater circuit comprises a falling edge adjustment inverter, which falling edge adjustment inverter can be adjusted to change the timing of the falling edges of the second gated clock signal.

10. Circuitry as in claim 9, wherein the feed-forward path of the rising clock edge generation circuit of the second clock gater circuit comprises a load-matching inverter, which load-matching inverter can be adjusted to match loads between the falling and rising clock edge generation circuits of the second clock gater circuit.

11. Circuitry as in claim 7, wherein:

a) the feedback path of the falling clock edge generation circuit of the second clock gater circuit is coupled to a first input of a logic gate, which logic gate forms a part of the feed-forward path of the falling clock edge generation circuit; and

b) the even number more inverters is coupled between the first clock input and logic gate of the second clock gater circuit.

12. Circuitry as in claim 11, wherein an input to the even number more inverters is directly coupled to the first clock input.

13. Circuitry as in claim 7, wherein the even number more inverters lies in the feed-forward path of the falling clock edge generation circuit of the second clock gater circuit.

14. Circuitry as in claim 13, wherein the feed-forward path of the rising clock edge generation circuit of the second clock gater circuit comprises a rising edge adjustment inverter, which rising edge adjustment inverter can be adjusted to change the timing of the rising edges of the second gated clock signal.

15. Circuitry as in claim 14, wherein the feed-forward path of the falling clock edge generation circuit of the second clock gater circuit comprises a load-matching inverter, which load-matching inverter can be adjusted to match loads between the falling and rising clock edge generation circuits of the second clock gater circuit.

16. Circuitry as in claim 7, wherein:

a) the feedback path of the rising clock edge generation circuit is coupled to a first input of a logic gate, which logic gate forms a part of the feed-forward path of the rising clock edge generation circuit; and

b) the even number more inverters is coupled between the second clock input and logic gate of the second clock gater circuit.

17. Circuitry as in claim 16, wherein an input to the even number more inverters is directly coupled to the second clock input.