# US 9,438,458 B1 · Method and apparatus for converting analog radio frequency (RF) signals to the digital domain in a multiband and multicarrier wireless communication system

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- Number: US 9,438,458 B1
- Document ID: US9438458B1
- Status: Granted
- Kind: B1
- Application number: 14/570,640
- Filed: 2014-12-15
- Granted: 2016-09-06
- Earliest claimed: 2014-02-14
- Assignees: Microsemi Storage Solutions (U.S.), Inc.
- Applicants: Pmc-Sierra US, Inc.
- Inventors: Ryan Santa; Bernard Guay
- Web page: https://patentgrep.com/patent/US9438458B1

## CPC

- H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)}
- H04B 1/0017: {Digital filtering (H04B1/001 takes precedence; digital filters per se H03H17/00)}
- H04B 1/707: using direct sequence modulation
- H04L 5/001: {the frequencies being arranged in component carriers}
- H04L 25/03012: {operating in the time domain (H04L25/03165, H04L25/03178 take precedence)}
- H04L 27/2334: {using filters}
- H04B 1/7115: Constructive combining of multi-path signals, i.e. RAKE receivers
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

A method and system are provided for converting wideband analog radio frequency (RF) signals to a digital domain. In an implementation, the system comprises: an amplifier for receiving and amplifying a first wideband analog RF signal comprising one or more first narrowband analog RF signals, each first narrowband analog RF signal occupying a distinct non-overlapping spectral band within a spectrum of the first wideband analog RF signal; N down converter modules; N analog-to-digital converters (ADCs); and a cross-connect for connecting any one of the N down converter modules to one or more of the N ADCs to analog-to-digital convert only the first narrowband analog RF signals occupying the distinct non-overlapping spectral bands. The method and system of the present disclosure track the occupied bandwidth of the narrowband analog RF signals that make up a wideband analog RF signal rather than a total bandwidth of the wideband analog RF signal.

## Claims

### Claim 1

A method of converting wideband analog radio frequency (RF) signals to a digital domain, the method comprising:
receiving a first wideband analog RF signal at an analog-to-digital converter system comprising N analog-to-digital converters (ADCs), wherein N is a positive integer greater than 1, the first wideband analog RF signal comprising one or more first narrowband analog RF signals, each of the first narrowband analog RF signal occupying a distinct non-overlapping spectral band within a spectrum of the first wideband analog RF signal, wherein a total of the bandwidths of the one or more first narrowband analog RF signals is less than a total bandwidth of the first wideband analog RF signal;
separating each of the first narrowband analog RF signal occupying the one distinct non-overlapping band from the first wideband analog RF signal using one of N down converter modules by tuning the one down converter module to a center frequency of one of the distinct non-overlapping bands;
cross-connecting any one of the N down converter modules to one or more of the N ADCs;
selectively enabling and disabling each of the N ADCs based on the number of first narrowband analog RF signals in the first wideband analog RF signal so that a first subset of the N ADCs is enabled to perform analog-to-digital conversion of the first narrowband analog RF signals and the other of the N ADCs outside of the first subset are disabled; and
analog-to-digital converting only the first narrowband analog RF signals occupying the distinct non-overlapping spectral bands using the enabled first subset of ADCs while not analog-to-digital converting the remainder of the first wideband analog RF signal.

### Claim 2 (depends on 1)

The method of claim 1, wherein separating the one or more first narrowband analog RF signals from the first wideband analog RF signal comprises:
down converting the first wideband analog RF signal to first pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center frequency of one of the distinct non-overlapping spectral bands; and
filtering the first pairs of orthogonal baseband analog signals to generate first pairs of filtered orthogonal baseband analog signals, each of the first pairs of filtered orthogonal baseband analog signals corresponding to one of the distinct narrowband analog RF signals.

### Claim 3 (depends on 2)

The method of claim 2, wherein analog-to-digital converting comprises:
converting each of the first pairs of filtered orthogonal baseband analog signals to pairs of digital signals.

### Claim 4 (depends on 2)

The method of claim 2, wherein down converting comprises:
amplifying each of the first pairs of orthogonal baseband analog signals.

### Claim 5 (depends on 4)

The method of claim 4, wherein filtering comprises:
filtering the first pairs of amplified orthogonal baseband analog signals to generate the first pairs of filtered orthogonal baseband analog signals.

### Claim 6 (depends on 2)

The method of claim 2, wherein the first pairs of orthogonal baseband signals include a first in phase baseband signal and a first quadrature baseband signal.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
receiving a second wideband analog RF signal at the analog-to-digital converter system, the second wideband analog RF signal comprising one or more second narrowband RF analog signals, each of the second narrowband analog RF signals occupying a distinct non-overlapping spectral band within a spectrum of the second wideband analog RF signal, wherein the first and second wideband analog RF signals are spectrally non-overlapping; and
selectively enabling and disabling each of the N ADCs so that a second subset of the N ADCs is enabled to perform analog-to-digital conversion of only the second narrowband RF analog signals occupying the distinct non-overlapping spectral bands within the spectrum of the second wideband analog RF signal, such that only the first and second subsets of the N ADCs are enabled and any other of the N ADCs outside of the first and second subsets are disabled.

### Claim 8 (depends on 7)

The method of claim 7, wherein analog-to-digital converting only the second narrowband analog RF signals occupying the distinct non-overlapping spectral bands comprises:
separating the one or more second narrowband analog RF signals from the second wideband analog RF signal.

### Claim 9 (depends on 8)

The method of claim 8, wherein separating the one or more second narrowband analog RF signals from the second wideband analog RF signal comprises:
down converting the second wideband analog RF signal to second pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center frequency of one of the distinct non-overlapping spectral bands; and
filtering the pairs of orthogonal baseband analog signals to generate pairs of filtered orthogonal baseband analog signals, each pair of filtered orthogonal baseband analog signals corresponding to one of the distinct narrowband analog RF signals.

### Claim 10

A system for converting wideband analog radio frequency (RF) signals to a digital domain, the system comprising:
a first amplifier for receiving and amplifying a first wideband analog RF signal comprising one or more first narrowband analog RF signals, each of the first narrowband analog RF signals occupying a distinct non-overlapping spectral band within a spectrum of the first wideband analog RF signal, wherein a total of the bandwidths of the one or more first narrowband analog RF signals is less than a total bandwidth of the first wideband analog RF signal;
N down converter modules, each down converter module tunable to a center frequency of one of the distinct non-overlapping bands to separate the first narrowband analog RF signal occupying the one distinct non-overlapping band from the first wideband analog RF signal;
N analog-to-digital converters (ADCs), wherein N is a positive integer greater than 1;
a first cross-connect for connecting any one of the N down converter modules to one or more of the N ADCs to analog-to-digital convert only the first narrowband analog RF signals occupying the distinct non-overlapping spectral bands while not analog-to-digital converting the remainder of the first wideband analog RF signal; and
a controller to selectively enable and disable each of the N ADCs based on the number of first narrowband analog RF signals in the first wideband analog RF signal so that a first subset of the N ADCs is enabled to perform analog-to-digital conversion of the first narrowband analog RF signals and the other of the N ADCs outside of the first subset are disabled.

### Claim 11 (depends on 10)

The system of claim 10, further comprising:
a second amplifier for receiving and amplifying a second wideband analog RF signal comprising one or more second narrowband analog RF signals, each of the second narrowband analog RF signals occupying a distinct non-overlapping spectral band within a spectrum of the second wideband analog RF signal, wherein the first and second wideband analog RF signals are spectrally non-overlapping; and
wherein the first cross-connect is configurable to connect any one of the N down converter modules to one or more of the N ADC modules, and the controller is configurable to selectively enable a second subset of the N ADCs to analog-to-digital convert only the second narrowband RF analog signals occupying the distinct non-overlapping spectral bands within the spectrum of the second wideband analog RF signal, such that only the first and second subsets of the N ADCs are enabled and any other of the N ADCs outside of the first and second subsets are disabled.

### Claim 12 (depends on 11)

The system of claim 11, wherein one or more of the N down converter modules is configured to separate the one or more second narrowband analog RF signals from the second wideband analog RF signal.

### Claim 13 (depends on 12)

The system of claim 12, wherein:
the one or more of the N down converter modules is configured to separate the one or more second narrowband analog RF signals from the first wideband analog RF signal by down converting the second wideband analog RF signal to second pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center frequency of one of the distinct non-overlapping spectral bands, and
the system further comprising:
a plurality of filters configured to filter the second pairs of orthogonal baseband analog signals to generate second pairs of filtered orthogonal baseband analog signals, each of the second pairs of filtered orthogonal baseband analog signals corresponding to one of the distinct narrowband analog RF signals.

### Claim 14 (depends on 10)

The system of claim 10, wherein:
one or more of the N down converter modules is configured to separate the one or more first narrowband analog RF signals from the first wideband analog RF signal by down converting the first wideband analog RF signal to first pairs of orthogonal baseband analog signals using a set of down conversion frequencies, where each down conversion frequency is tuned to a center frequency of one of the distinct non-overlapping spectral bands, and
the system further comprising:
a plurality of filters configured to filter the first pairs of orthogonal baseband analog signals to generate first pairs of filtered orthogonal baseband analog signals, each of the first pairs of filtered orthogonal baseband analog signals corresponding to one of the distinct narrowband analog RF signals.

### Claim 15 (depends on 14)

The system of claim 14, further configured such that the analog-to-digital conversion comprises converting each of the first pairs of filtered orthogonal baseband analog signals to pairs of digital signals.

### Claim 16 (depends on 14)

The system of claim 14, wherein at least one of the down converter modules comprises a pair of amplifiers configured to amplify each of the first pairs of orthogonal baseband analog signals, respectively.

### Claim 17 (depends on 16)

The system of claim 16, wherein the at least one down converter module comprises a pair of filters configured to filter the first pairs of amplified orthogonal baseband analog signals, respectively, to generate the first pairs of filtered orthogonal baseband analog signals.

### Claim 18 (depends on 14)

The system of claim 14, wherein the first pairs of orthogonal baseband signals include a first in phase baseband signal and a first quadrature baseband signal.

### Claim 19 (depends on 10)

The system of claim 10, wherein the number of ADCs in the first subset is less than N.

### Claim 20 (depends on 1)

The method of claim 1, wherein the number of ADCs in the first subset is less than N.