Circuits, systems, and methods for managing automatic gain control in quadrature signal paths of a receiver

Abstract

A system provides closed-loop gain control in a WCDMA mode and open loop control in an EDGE / GSM mode. Gain control is distributed across analog devices and a digital sealer in a wireless receiver. In the WCDMA mode, a loop filter generates an error signal that is forwarded to analog and digital control paths. The analog control path includes a first adder, a programmable hysteresis element, and a lookup table. The analog control signal is responsive to thresholds, which when used in conjunction with a previous gain value determine a new gain value. The digital control path includes a second adder, a programmable delay element, and a converter. A control word is responsive to a difference of the error signal, a calibration value, and the analog control signal. Blocker detection is provided in the WCDMA mode of operation. A controller sets system parameters using a state machine.

Description

Background technique [0001] Radio Frequency (RF) transceivers are found in many one-way and two-way communication devices such as portable communication devices, (cellular telephones), personal digital assistants (PDAs), and other communication devices. RF transceivers transmit and receive signals using whatever communication method is dictated by the particular communication system in which they operate. For example, communication methods usually include amplitude modulation, frequency modulation, phase modulation, or a combination of these, and in the Global System for Mobile Communications (GSM), which is a common mobile communication system using narrowband Time Division Multiple Access (TDMA), Gaussian minimum frequency shift key is used Control (GMSK) modulation scheme to transmit data. [0002] The deployment of new wireless systems presents unique challenges to mobile handset designers. To benefit from expanded capacity and increased data bandwidth, next generation h...

AI Technical Summary

Problems solved by technology

In addition, these prior art systems must constantly monitor and correct for changing signal conditions due to the relative movement between the mobile transceiver and the nearest base station and the relative movement of other objects in the path between the mobile transceiver and the nearest base station

These digital gain control systems typically do not provide accurate power control in environments where signal strength varies rapidly over a large dynamic range

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