Low Noise Amplifier for Multiple Channels

• US 20130154742A1
• Filed: 12/17/2012
• Published: 06/20/2013
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Samuels, Howard R.
• Granted Patent: US 9,041,463 B2
• Time in Patent Office: Days
• US Class Current: 330/260
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/082 for two degrees of freedom of movement of a single mass
• CPC Class Codes: H03F 1/26 Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• CPC Class Codes: H03F 2200/129 there being a feedback over the complete amplifier
• CPC Class Codes: H03F 2200/171 A filter circuit coupled to the output of an amplifier
• CPC Class Codes: H03F 2200/261 Amplifier which being suitable for instrumentation applications
• CPC Class Codes: H03F 2200/333 A frequency modulator or demodulator being used in the amplifier circuit
• CPC Class Codes: H03F 2203/45512 the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC
• CPC Class Codes: H03F 2203/45544 the IC comprising one or more capacitors, e.g. coupling capacitors
• CPC Class Codes: H03F 3/04 with semiconductor devices only
• CPC Class Codes: H03F 3/45071 with semiconductor devices only
• CPC Class Codes: H03F 3/45475 using IC blocks as the active amplifying circuit
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

An amplifier system has an amplifier for amplifying a plurality of input signals from a plurality of different channels, and a plurality of demodulators each operatively coupled with the amplifier for receiving amplified input signals from the amplifier. Each demodulator is configured to demodulate a single amplified input channel signal from a single channel of the plurality of different channels. The system thus also has a plurality of filters, coupled with each of the demodulators, for mitigating the noise.

Claims

1. An amplifier system comprising:

an amplifier for amplifying a plurality of input signals from a plurality of different channels;

a plurality of demodulators operatively coupled with the amplifier for receiving amplified input signals of the plurality of channels from the amplifier, each demodulator being configured to demodulate a single amplified input channel signal from a single channel of the plurality of different channels, each demodulator producing noise related to at least one of the channels other than the single channel;

a plurality of filters coupled with the demodulators, the filters mitigating the noise.

2. The amplifier system as defined by claim 1 wherein the noise comprises clock frequency noise.

3. The amplifier system as defined by claim 1 wherein the noise comprises high frequency noise, the filter comprising a low pass filter configured with a cutoff to mitigate the high frequency noise.

4. The amplifier system as defined by claim 1 wherein the input signals have clocks that are in quadrature.

5. The amplifier system as defined by claim 4 wherein the input signals have clocks that have substantially the same frequencies.

6. The amplifier system as defined by claim 1 wherein the input signals have clocks with coincident edges and frequencies that are related by multiples of 2 or multiples of 0.5.

7. The amplifier system as defined by claim 1 wherein each demodulator demodulates a signal for a different channel than those demodulated by the other demodulators.

8. The amplifier system as defined by claim 1 wherein the plurality of signals includes inertial signals produced from a MEMS device.

9. A system comprising:

a MEMS device producing a first signal in a first channel and a second signal in a second channel; and

an amplifier receiving the first and second signals and producing first and second output signals, the first and second output signals being in different channels.

10. The system as defined by claim 9 wherein the first channel relates to a first axis and the second channel relates to a second axis.

11. The system as defined by claim 9 wherein the first and second signals have clocks in quadrature.

12. The system as defined by claim 11 wherein the clocks of the first and second signals have different frequencies.

13. The system as defined by claim 11 wherein the clocks of the first and second signals have the same frequencies.

14. The system as defined by claim 9 wherein the amplifier comprises a plurality of different channels, the system further comprising a plurality of filters that each filter a different channel of the amplifier.

15. A method of processing a signal comprising:

controlling an amplifier comprising;

amplifying an input signal having a plurality of different channels to produce an amplified input signal having the plurality of different channels;

demodulating the amplified input signal to produce at least one demodulated signal for each channel, demodulating causing each demodulated signal to have noise relating to at least one other channel; and

filtering each demodulated signal to mitigate the noise to produce a baseband signal for each of the plurality of channels; and

forwarding each baseband signal from at least one output node.

16. The method as defined by claim 15 wherein each channel in the input signal has an associated clock, all of the clocks for each channel having coincident edges and frequencies that are related by multiples of 2 or multiples of 0.5.

17. The method defined by claim 15 wherein the noise comprises high frequency noise, filtering comprising low pass filtering using a cutoff to mitigate the high frequency noise.

18. The method as defined by claim 15 wherein each channel in the input signal has an associated clock, the input clocks being in quadrature.

19. The method as defined by claim 15 further comprising receiving the input signal from a MEMS device, the plurality of different channels relating to at least two orthogonal axes in a Cartesian coordinate system.

20. The method as defined by claim 15 wherein the amplifier comprises an amplifier for amplifying the input signal, a plurality of demodulators for demodulating the amplified input signal, and a plurality of filters for filtering the demodulated signals, each channel having at least one demodulator and at least one filter for its exclusive use.

21. The method as defined by claim 15 wherein amplifying, demodulating, and filtering are performed continuously without sampling.