Adjustable gain low noise amplifier

Abstract

The invention provides an adjustable gain low noise amplifier, wherein a predistorter compares gain control voltage Vc with reference voltage Vref, converts into first bias current Ibias, and the first bias current Ibias is supplied for an adjustable gain module; a minimum gain module provides minimum gain control and inputs second bias current Ibias2 for adjusting the gain; and the output of theadjustable gain module and the output of the minimum gain module are combined as the radio-frequency output of the adjustable gain low noise amplifier. Because the gain of the adjustable gain module is controlled by a bias signal after predistortion, the gain of the adjustable low noise amplifier near the reference voltage and the gain control voltage are in logarithm linear relation, and simultaneously the maximum gain and the minimum gain of the adjustable gain low noise amplifier are accurately controlled by arranging the minimum gain module. The adoption of bias current for controlling the gain has the advantage that when the signal is larger, the working current of the amplifier is greatly reduced, so that the power consumption is saved.

Description

technical field [0001] The invention relates to the field of signal and information processing, especially to radio frequency transmission and reception technology. Background technique [0002] At present, the implementation methods of the radio frequency receiving circuit include super regenerative structure, super heterodyne structure, low intermediate frequency structure, zero intermediate frequency structure and so on. figure 1 Shown is a simplified zero-IF receiving circuit. After the radio frequency signal is received by the antenna, it is amplified by the low-noise amplifier and mixed with the oscillation signal generated by the local oscillator to the intermediate frequency. The intermediate frequency signal is amplified by the first-stage intermediate frequency amplifier and enters the filter circuit. In addition to the out-of-band signal, the obtained baseband signal is then amplified by the secondary intermediate frequency amplifier for demodulation by the subseq...

AI Technical Summary

Problems solved by technology

The continuous time adjustable gain low noise amplifier (LNA) can be realized by adjusting the load size, increasing the pre / post attenuator, or adjusting the operating current. The variable load is generally composed of MOS resistors in the linear region, and the continuous time Most attenuators are based on MOS resistors, which are the same as the method of adjusting the working current. Since the I-V characteristics of MOS tubes satisfy the square rate relationship, the logarithmic linear relationship between gain and gain control voltage cannot be directly realized.

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