Systems and methods for synchronous demodulation

Patent metadata

Field	Value
Publication number	US-10469030-B2
Application number	US-201615575312-A
Country	US
Kind code	B2
Filing date	May 20, 2016
Priority date	May 20, 2015
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

Systems and methods for synchronous demodulation using passive sampled analog filtering are disclosed. A system for synchronous demodulation includes an input channel for accepting an input signal, a first passive sampled analog filter for filtering the input signal, a mixer for mixing the filtered input signal and outputting a mixed signal, a second passive sampled analog filter for filtering the mixed signal, and an output channel for outputting the filtered mixed signal.

First claim

What is claimed is:

1. A system for synchronous demodulation using passive sampled analog filtering, comprising:
an input channel for receiving an input signal;
a first passive sampled analog filter for sampling and filtering the input signal;
a mixer for mixing the filtered input signal from the first filter and outputting a mixed signal;
a second passive sampled analog filter for filtering the mixed signal; and
an output channel for outputting the filtered mixed signal.

2. The system of claim 1 , wherein the first filter and the mixer are combined in a single passive circuit block.

3. The system of claim 1 , further comprising a first active amplifier between the first filter and the mixer for amplifying the filtered signal.

4. The system of claim 3 , further comprising a second active amplifier between the mixer and the second filter for amplifying the mixed signal.

5. The system of claim 1 , wherein the first passive sampled analog filter is a programmable filter.

6. The system of claim 1 , wherein the first passive sampled analog filter is one of a low-pass filter, a band-pass filter, a high-pass filter, and a filter with an arbitrary filter shape.

7. The system of claim 1 , wherein the first passive analog filter is one of a FIR filter and an IIR filter.

8. The system of claim 1 , wherein the second passive sampled analog filter is a low pass filter.

9. The system of claim 1 , further comprising a clock generator for generating an excitation signal, and wherein the excitation signal is modified by a target element, and the modified excitation signal is the input signal.

10. The system of claim 9 , wherein the target element is a body part and wherein the system measures bioimpedance of the body part.

11. The system of claim 9 , wherein the clock generator generates a reference signal, and wherein the reference signal is mixed with the filtered input signal at the mixer.

12. The system of claim 9 , wherein the target element is one of a sensor and a transformer.

13. A method for synchronous demodulation using passive sampled analog filtering, comprising:
presenting an excitation signal to a target element;
receiving, at an input, a modified signal from the target element;
sampling and filtering, using a passive sampled analog filter, the modified signal to remove noise;
mixing the filtered signal with a reference signal from a clock generator;
filtering, using a second passive sampled analog filter, the mixed signal; and
outputting, from the second passive sampled analog filter, a signal representing characteristics of the target element.

14. The method of claim 13 , wherein presenting the excitation signal includes presenting a current to the target element, and wherein receiving a modified signal includes receiving a voltage.

15. The method of claim 13 , wherein presenting the excitation signal includes presenting a voltage to the target element, and wherein receiving a modified signal includes receiving a current.

16. The method of claim 13 , wherein outputting the signal includes outputting an I-component of the signal and outputting a Q-component of the signal.

17. A synchronous demodulation system using passive sampled analog filtering, comprising:
a clock generator for generating an excitation signal;
an input channel for receiving a modified excitation signal;
means for passively sampling, filtering and mixing the modified excitation signal to synchronously demodulate the modified excitation signal and generate a demodulated output signal.

18. The system of claim 17 , wherein the means for passively filtering the modified excitation signal includes a passive sampled analog filter.

19. The system of claim 18 , wherein the passive sampled analog filter is one of a low-pass filter, a band-pass filter, a high-pass filter, and a filter with an arbitrary filter shape.

20. The system of claim 17 , wherein the means for mixing the modified excitation signal include a mixer, and wherein the mixer is one of a two-level mixer, a three-level mixer, and a mixer with greater than three levels.

Assignees

• Analog Devices Inc

Inventors

• Nestler Eric G
• Magruder Christopher Lynn
• Harrington John Brian

Classifications

• H03H11/34

  Networks for connecting several sources or loads working on different frequencies or frequency bands, to a common load or source · CPC title

• H03D1/22 Primary

  Homodyne or synchrodyne circuits {(receiver circuits H04B1/30)} · CPC title

• H03H11/04

  Frequency selective two-port networks · CPC title

• H04L27/22

  Demodulator circuits; Receiver circuits · CPC title

• H03D7/12 Primary

  by means of semiconductor devices having more than two electrodes (H03D7/14 - H03D7/22 take precedence) · CPC title