# US 2013/0154742 A1 · Low Noise Amplifier for Multiple Channels

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- Number: US 2013/0154742 A1
- Document ID: US20130154742A1
- Status: Published application
- Kind: A1
- Application number: 13/716,258
- Filed: 2012-12-17
- Published: 2013-06-20
- Earliest claimed: 2011-12-16
- Assignees: Analog Devices, Inc.
- Inventors: Howard R. Samuels
- Web page: https://patentgrep.com/patent/US20130154742A1

## CPC

- H03F 1/26: Modifications of amplifiers to reduce influence of noise generated by amplifying elements
- G01P 15/125: by capacitive pick-up
- G01P 15/18: in two or more dimensions
- H03F 3/04: with semiconductor devices only
- H03F 3/45071: {with semiconductor devices only}
- H03F 3/45475: {using IC blocks as the active amplifying circuit}
- 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)}
- G01P 2015/082: {for two degrees of freedom of movement of a single mass}
- H03F 2200/129: there being a feedback over the complete amplifier
- H03F 2200/171: A filter circuit coupled to the output of an amplifier
- H03F 2200/261: Amplifier which being suitable for instrumentation applications
- H03F 2200/333: A frequency modulator or demodulator being used in the amplifier circuit
- H03F 2203/45512: the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC
- H03F 2203/45544: the IC comprising one or more capacitors, e.g. coupling capacitors
- H03F: AMPLIFIERS
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})

## 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

### Claim 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.

### Claim 2 (depends on 1)

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

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 4)

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

### Claim 6 (depends on 1)

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.

### Claim 7 (depends on 1)

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.

### Claim 8 (depends on 1)

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

### Claim 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.

### Claim 10 (depends on 9)

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.

### Claim 11 (depends on 9)

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

### Claim 12 (depends on 11)

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

### Claim 13 (depends on 11)

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

### Claim 14 (depends on 9)

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.

### Claim 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.

### Claim 16 (depends on 15)

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.

### Claim 17 (depends on 15)

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.

### Claim 18 (depends on 15)

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

### Claim 19 (depends on 15)

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.

### Claim 20 (depends on 15)

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.

### Claim 21 (depends on 15)

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