Automatic gain control of a receiver circuit

Active Publication Date: 2014-06-19
EM MICROELECTRONIC-MARIN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an improved receiver circuit with a more robust automatic gain control. It prevents the effect of inevitable offset signals of components of the AGC on the operation of the automatic gain control and the receiver circuit, reducing power consumption. The invention is also insensitive to inevitable variations due to manufacturing processes, making use of low-priced electronic components without degrading input power sensitivity and linearity and reducing production costs.

Problems solved by technology

Inter-modulation is rarely desirable in radio processing.
For radio reception, strong adjacent channels can interfere with the desired signal resulting in loss of reception.
For mobile application scenarios this may lead to unacceptably short battery life.
Reducing the current consumption of the RF receiver circuit either degrades sensitivity, linearity, or both.
Moreover, if the gain of a receiver is not properly adjusted for incoming signal strength of a desired signal, the receiver may be improperly insensitive or overly sensitive.
An insensitive receiver is likely to be a poor receiver of a low level desired signal.
An overly sensitive receiver is more susceptible to nearby interferers.
If for instance the RF input power is comparatively large, the comparator causes the up / down counter to count up, thereby decreasing the gain of the LNA.
Even though existing AGC designs allow for a substantive reduction of power consumption a problem may be encountered when the LNA is in a low-gain state and when an RF signal of comparatively high power is abruptly no longer available.

Method used

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  • Automatic gain control of a receiver circuit
  • Automatic gain control of a receiver circuit

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Embodiment Construction

[0047]In FIG. 1 a schematic block diagram of a receiver circuit 10 is presented. The receiver circuit 10 comprises an antenna 12 adapted to receive electromagnetic radiation and to provide respective electrical signals to an input amplifier 14, which is preferably implemented as LNA. The output of the amplifier 14 is coupled with the input of a down-converter mixer 16. Downstream of the mixer 16 there is provided a low-pass or band-pass filter 18 as well as an analogue-to-digital converter (ADC) 20. The output of the ADC 20 is finally provided to a demodulator 22 by way of which the electrical signals received by the antenna 12 can be further processed.

[0048]The receiver circuit 10 further comprises an automatic gain control circuit 30. As indicated in FIG. 1, the AGC comprises a comparator 36, a peak detector 32 and a threshold value generator 34, the latter of which being preferably implemented as a DAC. The output of the comparator 36 is connected with an up / down counter 38.

[0049...

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Abstract

The present invention relates to a receiver circuit for processing of electrical signals, and comprising:an antenna (12),at least one amplifier (14) coupled to the output of the antenna (12),an automatic gain control circuit (30) coupled to the at least one amplifier (14) to modify a gain thereof, andat least one voltage offset-compensating circuit (50) embedded in the automatic gain control circuit (30) and comprising a clock generator (40) and at least one capacitor (42, 44) to effectively compensate an offset voltage.

Description

FIELD OF THE INVENTION[0001]The present invention relates to the field of receiver circuits and in particular to RF receiver circuits featuring an automatic gain control (AGC). Moreover, the invention relates to optimization of automatic gain control circuits in RF receiver assemblies for reducing power consumption, and improving sensitivity and linearity of such receiver circuits.BACKGROUND OF THE INVENTION[0002]Analogue circuits in an RF receiver exhibit comparatively high power consumption in order to provide a good linearity regarding signals of high input power as well as good sensitivity regarding signals of low input power.[0003]Linearity of an amplifier refers to the consistent transfer function of an amplifier for small or large signals. Measures of degradation of linearity are for instance signal compression or inter-modulation / distortion of large input signals. Inter-modulation / distortion refers to the amplitude modulation of signals containing two or more different frequ...

Claims

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Application Information

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IPC IPC(8): H04B1/16
CPCH04B1/16H03G3/3078
InventorMORIN, MARCPITTORINO, TINDARO
OwnerEM MICROELECTRONIC-MARIN