Low noise amplifier and tuner including the same

Abstract

The invention provides a low noise amplifier and a tuner comprising the low noise amplifier; the low noise amplifier comprises: a first active element which is provided with a first end, a second end and a third end, wherein, the first end is connected with an input end; a second active element which is provided with a first end, a second end and a third end, wherein, the first end is connected with another input end; a first adjustable attenuator, the first end of which is connected with the first end of the first active element while the second end of which is connected with the second end of the second active element; and a second adjustable attenuator, the first end of which is connected with the second end of the first active element while the second end of which is connected with the first end of the second active element. The invention provides a new circuit structure, which causes the resistance to be changed fixedly within very small scope when the low noise amplifier of the invention regulates gain, therefore, the low noise amplifier and the tuner of the invention can be caused to be maintained in the optimal resistance matching state.

Description

technical field [0001] The present invention relates to a low noise amplifier, in particular to a low noise amplifier configured in a tuner. Background technique [0002] With the advancement of communication technology and compression technology, the global TV broadcasting system has been converted from analog TV broadcasting to digital TV broadcasting. The transformation of digital TV broadcasting will drive the rapid development of related industries, such as digital TV (HDTV) and set-top box (Set-Top-Box; STB). Not only that, but the future will develop towards mobile digital TV reception, so it is no longer a dream to receive TV programs anytime and anywhere, and tuner circuits play a pivotal role in digital TV sets and set-top boxes or future mobile receiving systems. [0003] Referring to FIG. 1A , it is a schematic diagram of main parts of a conventional single conversion (single conversion) tuner, and the tuner may be a superheterodyne tuner. As shown in Figure 1A...

AI Technical Summary

Problems solved by technology

[0008] However, when the gain of FIG. 2A and FIG. 2B is changed, such as adjusting to the maximum gain, the input impedance value will change too much, so that the input impedance of the low noise amplifier cannot be matched to the optimum, and thus the feedback loss of the tuner (return loss, return loss) is reduced, and it will also reduce the noise suppression ability of broadband signals

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