Quadrature receiver sampling architecture
View Patent ↗Quadrature receiver sampling architecture. A signal ADC performs analog to digital conversion for both I and Q streams. An analog MUX selects the appropriate I and the Q baseband analog input streams for input to the ADC at the appropriate time. A digital filter may also be employed to compensate for any introduced delay between the samples of the I and Q channel when seeking to recover the symbols that have been transmitted to a communication receiver that employs this quadrature receiver architecture and/or signal processing. In one embodiment, if an ADC is clocked at a rate of substantially twice the sample rate of the I and Q channels, there will be a one-half sample clock delay between the digital I and digital Q data at the output of the ADC. This delay is then removed before the demodulator processes the input signals to recover the transmitted symbols.
1. A communication device, comprising:
a multiplexor (MUX) configured to:
receive an analog in-phase (I) stream;
receive an analog quadrature (Q) stream; and
output an analog stream that alternates between the analog I stream and the analog Q stream based upon a clocked selector input;
an analog-to-digital converter (ADC) configured to:
receive the analog stream; and
sample the analog stream thereby generating a digital stream that includes alternating digital I information and digital Q information based upon the clocked selector input;
a de-multiplexor (DE-MUX) configured to receive the digital stream that includes the alternating digital I information and the digital Q information and alternately extracting a digital I stream and a digital Q stream from the digital stream based upon a slower clock rate with respect to the clocked selector input; and
a digital signal processor (DSP) configured to process at least one of the digital I stream and the digital Q stream to compensate for an alternating analog-to-digital conversion introduced effect thereon.
2. The communication device of claim 1 , further comprising:
a sample and hold module, interposed between the MUX and the ADC, configured to process the analog stream to ensure proper sampling of the analog stream by the ADC.
3. The communication device of claim 1 , wherein:
the alternating analog-to-digital conversion introduced effect is a delay between the digital I stream and the digital Q stream introduced by using the ADC to perform the sampling of the analog stream that includes alternating digital I information and digital Q information.
4. The communication device of claim 1 , wherein:
the DSP is configured to perform at least one of decimation, de-rotation, and delay compensation on at least one of the digital I stream and the digital Q stream to compensate for the alternating analog-to-digital conversion introduced effect.
5. The communication device of claim 1 , wherein:
the communication device is a wireless communication device that is implemented within a wireless communication system.
6. A method performed by a receiver, comprising:
receiving, by the receiver, an analog in-phase (I) stream and an analog quadrature (Q) stream; and
forming and outputting an analog stream that alternates between the analog I stream and the analog Q stream based upon a clocked frequency;
digitally sampling the analog stream with an analog to digital converter (ADC), thereby generating a digital stream that includes alternating digital I information and digital Q information based upon the clocked frequency;
alternately extracting a digital I stream and a digital Q stream from the digital stream based upon a slower clocked rate with respect to the clocked frequency; and
processing at least one of the digital I stream and the digital Q stream to compensate for a digital sampling effect introduced thereon.
7. The method of claim 6 , wherein:
the digital sampling effect is a delay between the digital I stream and the digital Q stream introduced when the ADC is a single ADC that performs the digital sampling of the analog stream that includes alternating digital I information and digital Q information.
8. The method of claim 6 , wherein:
the receiver is included with a wireless communication device of a wireless communication system.