Method and apparatus for improved zero intermediate frequency receiver latency

• US 5,710,998 A
• Filed: 12/19/1995
• Issued: 01/20/1998
• Est. Priority Date: 12/19/1995
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Opas, George Francis
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US08/574,542
• Time in Patent Office: 763 Days
• Field of Search: 455/209, 455/208, 455/314, 455/315, 455/324, 455/207, 455/316, 455/196.1, 455/205, 455/206, 455/258, 455/310, 455/255, 375/329, 329/304, 329/306
• US Class Current: 455/324
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A transceiver (10) in a first embodiment includes a zero intermediate frequency (ZIF) receiver (11), which achieves high throughput operation by reducing receiver latency time due to receiver response within a receiver pass band to carrier spectral components of a modulated carrier frequency. During a receive mode, a receiver local oscillator (LO) frequency is offset from the carrier frequency within the receiver pass band, preferably as determined by worst case errors in the carrier frequency and the LO frequency. During a transmit mode, the receiver LO frequency is modulated in such a way as to suppress the LO center frequency component in the modulated spectrum.

Claims

1. A receiver comprising:

a zero intermediate frequency (ZIF) receiver having a receiver bandwidth and a first input for receiving a carrier frequency having an associated carrier frequency error; and

a receiver local oscillator source having an output which couples a local oscillator frequency to a second input of the ZIF receiver, the local oscillator frequency being offset in frequency from the carrier frequency by an offset greater than a sum of an absolute value of frequency error in the receive local oscillator and an absolute value of the frequency error in the carrier.

2. A receiver comprising:

a zero intermediate frequency (ZIF) receiver having a receiver bandwidth and a first input for receiving a carrier frequency having an associated carrier frequency error; and

a receiver local oscillator source having an output which couples a local oscillator frequency to a second input of the ZIF receiver, the local oscillator frequency being offset in frequency from the carrier frequency by an offset within the receiver bandwidth,

wherein the local oscillator source is such that the local oscillator frequency is less than the carrier frequency,

wherein the local oscillator frequency has a local oscillator frequency error, the offset of the local oscillator frequency is below the carrier frequency, the local oscillator source being set such that the offset is greater than a sum of the carrier frequency error and the local oscillator frequency error.

3. A receiver comprising:

a zero intermediate frequency (ZIF) receiver having a receiver bandwidth and a first input for receiving a carrier frequency having an associated carrier frequency error; and

a receiver local oscillator source having an output which couples a local oscillator frequency to a second input of the ZIF receiver, the local oscillator frequency being offset in frequency from the carrier frequency by an offset within the receiver bandwidth,

wherein the local oscillator source is set such that the local oscillator frequency is greater than the carrier frequency,

wherein the local oscillator frequency has a local oscillator frequency error, the offset of the local oscillator frequency is greater than the carrier frequency, and the local oscillator source is set such that the offset is greater than a sum of the carrier frequency error and the local oscillator frequency error.

4. A method of reducing receiver latency time due to receiver response within a receiver bandwidth to carrier spectral components of a modulated career frequency, comprising:

offsetting a receive local oscillator frequency in a receive mode from the carrier frequency such that a center frequency component of the receive local oscillator frequency is offset from the carrier frequency by an amount greater than the sum of an absolute value of frequency errors of the carrier frequency and an absolute value of frequency errors of the receive local oscillator.

5. A method of reducing receiver latency time due to receiver response within a receiver bandwidth to carrier spectral components of a modulated carrier frequency, comprising:

offsetting a receive local oscillator frequency in a receive mode from the carrier frequency such that a center frequency component of the receive local oscillator frequency is offset from the carrier frequency by an amount determined by frequency errors of the carrier frequency and the receive local oscillator frequency,

wherein offsetting the receive local oscillator frequency in receive mode from the carrier frequency by an amount determined by a frequency error of the carrier frequency and a frequency error of the receive local oscillator frequency includes determining an amount of frequency offset greater than a sum of an absolute value of the frequency error of the receive local oscillator frequency and an absolute value of the frequency error of the carrier frequency resulting from one of a group consisting of one of a minimum or maximum of the carrier frequency and one of a minimum or maximum of the receive local oscillator frequency.

6. A method of reducing receiver latency time due to receiver response within a receiver bandwidth to carrier spectral components of a modulated carrier frequency, comprising:

offsetting a receive local oscillator frequency in a receive mode from the carrier frequency such that a center frequency component of the receive local oscillator frequency is offset from the carrier frequency by an amount determined by frequency errors of the carrier frequency and the receive local oscillator frequency,

wherein offsetting the receive local oscillator frequency in receive mode from the carrier frequency by an amount determined by a frequency error of the carrier frequency and a frequency error of the receive local oscillator frequency includes determining an amount of frequency offset greater than a sum of an absolute value of the frequency error of the receive local oscillator frequency and an absolute value of the frequency error of the carrier frequency resulting from one of a group consisting of one of a minimum or maximum of the carrier frequency and one of a minimum or maximum of the receive local oscillator frequency

wherein determining the amount of frequency offset includes setting the receive local oscillator frequency to a lower frequency than the carrier frequency, and setting the frequency offset to a margin value greater than a separation between a minimum carrier frequency and a maximum receive local oscillator frequency.

7. A method of reducing receiver latency time due to receiver response within a receiver bandwidth to carrier spectral components of a modulated carrier frequency, comprising:

offsetting a receive local oscillator frequency in a receive mode from the carrier frequency such that a center frequency component of the receive local oscillator frequency is offset from the carrier frequency by an amount determined by frequency errors of the carrier frequency and the receive local oscillator frequency,

wherein offsetting the receive local oscillator frequency in receive mode from the carrier frequency by an amount determined by a frequency error of the carrier frequency and a frequency error of the receive local oscillator frequency includes determining an amount of frequency offset greater than a sum of an absolute value of the frequency error of the receive local oscillator frequency and an absolute value of the frequency error of the carrier frequency resulting from one of a group consisting of one of a minimum or maximum of the carrier frequency and one of a minimum or maximum of the receive local oscillator frequency,

wherein determining the amount of frequency offset includes setting the local oscillator frequency to a higher frequency than the carrier frequency and setting the frequency offset to a margin value greater than a separation between a maximum carrier frequency and a minimum receive local oscillator frequency.