Broadcom Corporation

Nokia Mobile Phones Limited

Zhongming Shi

Arya Behzad

Ahmadreza Rofougaran

Ken Hsu

Kim Kaltiokallio

Reza Rofougaran

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.

Direct conversion RF transceiver for wireless communication

Direct conversion RF transceiver for wireless communications

A single chip radio transceiver includes circuitry that enables received wideband RF signals to be down-converted to baseband frequencies and baseband 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 a local oscillation 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.

Direct conversion RF transceiver with automatic frequency control

A single chip radio transceiver includes circuitry that enables received RF signals to be down-converted to baseband frequencies and baseband signals to be up-converted to 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, received signal strength indicators for adjusting frontal and rear amplification stages accordingly, and, finally, filtering circuitry to filter high and low frequency interfering signals, including DC offset. A radio frequency (RF) variable gain amplifier (VGA) includes a power amplifier in a direct conversion radio transceiver that includes a gain determination module that reduces an input gain level to the power amplifier to adjust the output power level of the power amplifier according to temperature indications to maintain reliable operation or power level indications to maintain a constant output power level.

Direct conversion RF transceiver with automatic transmit power control

A variable gain amplifier includes circuit elements that may be partially powered down during transmit modes of operation and that may be powered back up whenever the radio transceiver receives a data packet within a specified settle time even for high throughput RF communications. The radio transceiver circuit may be powered down even in high throughput communications during a transmit mode to reduce power consumption. A DC offset cancellation block is operably coupled to the variable gain block to substantially remove any DC offset from the amplified output. The variable gain amplifier is further able to provide DC offset cancellation within the required settle time by holding the offset value during a dormant mode of operation. Further, the variable gain amplifier transitions from a first gain control value to a second gain control value and further modifies its internal settle time from a first value to a second value to enable the variable gain amplifier to reach a steady state within the required settle time whenever required. The settle time transitions from the second value back to the first value after a specified period of time.

Fast settling variable gain amplifier with DC offset cancellation

Apparatus, and an associated method, for the IF stage of a receiver, such as the receive portion of a multi-mode mobile station. Direct conversion of an IF-stage receive signal is made into the digital domain through the use of a &Sgr;&Dgr; analog-to-digital converter. Increased portions of the receiver processes signals in the digital domain using digital-domain circuitry.

Apparatus and associated method, for operating on receive signals received at a receiver

A demodulator subsystem incorporates second-order filtering for use within a sigma-delta DAC. A conventional demodulator is modified to include circuitry which manifests a second-order filtering response to the output of the demodulator. The added circuitry includes an additional pair of phased switched capacitor legs and a fixed capacitor. The combination of the additional circuitry with the existing phase switched and fixed capacitors of the conventional demodulator creates an additional pole which provides second order filtering to the demodulator output, effectively eliminating the high-order post filtering and minimizing both the circuit area required for implementation of the demodulator and its power consumption.

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San Diego, CA, United States of America

Zhongming Shi