Continuous-time sampler circuits

Patent metadata

Field	Value
Publication number	US-11063794-B2
Application number	US-202016833177-A
Country	US
Kind code	B2
Filing date	Mar 27, 2020
Priority date	Feb 14, 2018
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A continuous-time sampler has series-connected delay lines with intermediate output taps between the delay lines. Signal from an output tap can be buffered by an optional voltage buffer for performance. A corresponding controlled switch is provided with each output tap to connect the output tap to an output of the continuous-time sampler. The delay lines store a continuous-time input signal waveform within the propagation delays. Controlling the switches corresponding to the output taps with pulses that match the propagation delays can yield a same input signal value at the output. The continuous-time sampler effectively “holds” or provides the input signal value at the output for further processing without requiring switched-capacitor circuits that sample the input signal value onto some capacitor. In some cases, the continuous-time sampler can be a recursively-connected delay line. The continuous-time sampler can be used as the front end sampler in a variety of analog-to-digital converters.

First claim

What is claimed is:

1. A method for sampling, comprising:
capturing, by one or more recursively-connected delay lines, time-shifted waveforms of a continuous-time input signal received at an input of the one or more recursively-connected delay lines; and
evaluating, at a plurality of clock edges, a same signal value from the time-shifted waveforms of the continuous-time input signal, at an output of the one or more recursively-connected delay lines.

2. The method of claim 1 , further comprising:
disconnecting a tab of a first recursively-connected delay line from receiving the continuous-time input signal; and
connecting the tab of the first recursively-connected delay line to receive a delayed signal generated by the first recursively-connected delay line.

3. A recursive continuous-time sampler, comprising:
a recursively-connected delay line having a first terminal and a second terminal;
an input tap;
a switch controllable to couple the input tap to an input of the recursive continuous-time sampler, or to couple the input tap to the second terminal of the recursively-connected delay line;
a buffer to buffer a signal at the input tap; and
an output tap at an output of the buffer;
wherein the second terminal of the recursively-connected delay line receives a signal from the output tap.

4. The recursive continuous-time sampler of claim 3 , further comprising:
a resistor between the output tap and the second terminal of the recursively-connected delay line.

5. The recursive continuous-time sampler of claim 3 , wherein:
the output tap is an output of the recursive continuous-time sampler.

6. The recursive continuous-time sampler of claim 3 , further comprising:
a grounded resistor at the input tap.

7. The recursive continuous-time sampler of claim 3 , wherein:
the buffer is a voltage buffer.

8. The recursive continuous-time sampler of claim 3 , wherein:
the buffer has a gain of 2.

9. The recursive continuous-time sampler of claim 3 , wherein:
the input tap connects to the input of the recursive continuous-time sampler, using the switch, to receive a continuous-time input signal.

10. The recursive continuous-time sampler of claim 3 , wherein:
the input tap connects to the second terminal of the recursively-connected delay line, using the switch, to form a recursive loop.

11. The recursive continuous-time sampler of claim 3 , wherein:
the recursively-connected delay line captures time-shifted waveforms of a continuous-time input signal.

12. The recursive continuous-time sampler of claim 3 , wherein:
the output tap of the recursive continuous-time sampler makes time-shifted waveforms of a continuous-time input signal received at the input of the recursive continuous-time sampler available for evaluation.

13. The recursive continuous-time sampler of claim 3 , wherein:
at a plurality of clock edges, a same signal value of a continuous-time input signal received at the input of the recursive continuous-time sampler, is evaluated from time-shifted waveforms of the continuous-time input signal stored in the recursively-connected delay line.

14. The recursive continuous-time sampler of claim 3 , wherein:
the output tap of the recursive continuous-time sampler is coupled to an input of an analog-to-digital converter.

15. The recursive continuous-time sampler of claim 3 , wherein:
the output tap of the recursive continuous-time sampler is coupled to an input of a further recursive continuous-time sampler.

16. A method for sampling, comprising:
connecting an input tap to an input;
propagating a continuous-time signal received at the input through a buffer and to a first terminal of a recursively-connected delay line;
disconnecting the input tap from the input;
connecting the input tap to a second terminal of the recursively-connected delay line;
receiving a delayed version of the continuous-time signal at the input tap; and
outputting the delayed version of the continuous-time signal, at an output tap between the buffer and the first terminal of the recursively-connected delay line.

17. The method of claim 16 , further comprising:
at a plurality of clock edges, evaluating a same signal value of the continuous-time signal at the output tap.

18. The method of claim 16 , further comprising:
at a plurality of clock edges, evaluating a same signal value of the continuous-time signal at the output tap, by an analog-to-digital converter.

19. The method of claim 16 , wherein:
propagating the continuous-time signal through a buffer comprises applying a gain of 2 to the continuous-time signal.

20. The method of claim 16 , wherein:
the recursively-connected delay line captures time-shifted waveforms of the continuous-time signal.

Assignees

• Analog Devices International Unlimited Co

Inventors

• Shibata Hajime
• Holford Brian
• Caldwell Trevor Clifford
• Devarajan Siddharth

Classifications

• G01R19/257

  using analogue/digital converters of the type with comparison of different reference values with the value of voltage or current, e.g. using step-by-step method · CPC title

• G01R13/34

  Circuits for representing a single waveform by sampling, e.g. for very high frequencies · CPC title

• H03M1/1245

  Details of sampling arrangements or methods · CPC title

• G11C7/222

  Clock generating, synchronizing or distributing circuits within memory device · CPC title

• G11C27/024

  using a capacitive memory element (G11C27/04 takes precedence) · CPC title