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US 7,733,981 B2Granted
Direct conversion RF transceiver for wireless communications
AssigneeBroadcom Corporation
InventorsZhongming Shi, Ahmadreza (Reza) Rofougaran, Arya Reza Behzad
Life of this patent
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Abstract
A single chip radio transceiver includes circuitry that enables received wideband RF signals to be down converted to base band frequencies and base band signals to be up converted to wideband RF signals prior to transmission without requiring conversion to an intermediate frequency. The circuitry includes a low noise amplifier, automatic frequency control circuitry for aligning the LO frequency with the frequency of the received RF signals, signal power measuring circuitry for measuring the signal to signal and power ratio and for adjusting frontal and rear amplification stages accordingly, and finally, filtering circuitry to filter high and low frequency interfering signals including DC offset.
Claims20
A transceiver, comprising:
- a transceiver port comprising an antenna for receiving and transmitting wireless communication signals at radio frequency;
- a receive path coupled to receive ingoing radio frequency (RF) signals from the transceiver port and coupled to produce ingoing digital signals to a transceiver processor;
- down conversion circuitry disposed within the receive path and coupled to receive the ingoing RF signals wherein the down conversion circuitry produces down-converted communication signals based on the received ingoing RF signals;
- automatic frequency control circuit that comprises:
- an RF signal processing portion that supports down converting ingoing signals from RF and up-converting outgoing signals to RF;
- a first frequency oscillation block generates a local oscillation based upon a frequency specified in a received pilot signal;
- a first mixing element that mixes a divided oscillation based upon the local oscillation and an oscillation correction signal;
- a frequency correction block that generates the oscillation correction signal having an oscillating signal form for adjusting a frequency of the divided local oscillation, wherein the oscillation correction signal is based on a difference between a center frequency of the ingoing RF signals and an expected center frequency of the ingoing RF signals;
- a plurality of amplifiers operably disposed within the receive path including a low noise amplifier operably disposed in the receive path between the transceiver port and the down conversion circuitry;
- received signal strength indication circuitry for measuring signal and interference power levels from a first node and for measuring signal power levels from a second node;
- and
- wherein the transceiver:
- determines a ratio of the signal power level in relation to the signal and interference power level;
- and
- reciprocally adjusts a low noise amplifier gain setting and a gain setting of at least one other amplifier of the plurality of amplifiers operably disposed within the receive path to maintain a constant total gain in the receive path based upon the determined ratio.
12 more elements
A transceiver, comprising;
- a transceiver port comprising an antenna for receiving and transmitting radio frequency communication signals wherein received signals are processed in a receive circuit path;
- automatic frequency control circuitry for producing an adjusted local oscillation frequency (LO);
- mixing circuitry for down converting the received radio frequency (RF) signal based upon an LO that is further based upon a receive pilot signal and upon the adjusted LO;
- received signal strength indication circuitry for measuring power levels of signal and interference from a plurality of nodes disposed within the receive circuit path;
- a plurality of amplifiers operably disposed within the receive circuit path;
- wherein the transceiver adjusts relative power levels of the plurality of amplifiers operably disposed within the receive circuit path to maintain a constant total amplification based upon measured power levels of signal and interference;
- and
- wherein automatic frequency control circuitry comprises:
- phase locked loop circuitry that generates a coarsely tuned local oscillation frequency in an analog portion of the receive circuit path based upon a frequency specified within a pilot signal;
- digital frequency correction logic that generates a digital local oscillation correction signal based on a received signal produced by the analog portion of the receive circuit path;
- and
- wherein the automatic frequency control circuitry generates a finely tuned local oscillation frequency in an analog portion having an oscillating signal form of the receive circuit path based on the digital local oscillation correction signal and on the coarsely tuned local oscillation.
9 more elements
A method in a high data rate communication transceiver comprising:
- receiving and amplifying wideband or high data rate radio frequency (RF) communication signals in a receive circuit path of the transceiver;
- generating a local oscillation (LO) based upon a frequency specified by a received pilot signal;
- generating a frequency corrected LO;
- mixing with frequency corrected LO with the LO to create an adjusted LO;
- down converting the received signals from RF to a lower frequency based upon the adjusted LO;
- producing a digital ingoing signal to a processing block;
- adjusting the LO with a correction signal;
- down converting the received RF communication signals with the adjusted LO to produce ingoing communication signals;
- determining a difference between an expected center channel frequency and a received center channel frequency;
- based on the determined difference, generating a frequency correction input having an oscillating signal form to adjust a local oscillation frequency to adjust a center frequency of a down converted signal;
- measuring power levels of the ingoing communication signals at a plurality of nodes disposed within a receive circuit path;
- and
- adjusting amplification levels in the receive circuit path based upon the measured power levels.
10 more elements
Dependencies are inferred from the claim text.