Low Noise Amplifier
As low noise amplifier and low noise amplifier (LNA ) refers to a specific type of electronic amplifier, the circuit technology characterized by special low noise to amplify extremely weak signals without equal implement the entire frequency band in lower frequencies. Special characteristic of a LNA is the noise figure.
In satellite communications the signal received by a parabolic antenna, first enters a LNA, to then be fed either directly into a cable of the reinforcement or to be supplied to a next stage, which then implements a frequency conversion to the signal to better over a cable to be transmitted frequencies to mix down, such as a low noise block converter (LNB). The signal is fed directly into the next transmission unit - in the case of the LNA, this is the Connection may be, in the case of the LNBs Umsetzblock before signaling. Therefore, a LNA is - as opposed to an LNB - even for interconnecting several parabolic mirrors to form an array. In this case, however, each antenna must be adjusted separately in the phase position by being moved millimeter by millimeter forward or backward ( toward the transmitter ). Due to the relatively large line loss, the cables are doing to keep extremely short. Therefore LNAs are only used in exceptional cases, eg when the GPS antennas. Instead, the signal is directly in the device blocks implemented at lower frequencies and fed with significantly less loss in the cable - this combination of LNA and block converter is one LNB.
In the receive path of a mobile phone is also an LNA to find. It there forms the first link in the analog signal processing chain and is integrated in the " analog front end ". By integrating no adjustment to line impedances output side is necessary because the next component - usually a mixer for frequency conversion into the baseband - directly follows and can be easily implemented with a high input resistance. The gain of a LNA is highly dependent on frequency, so that the LNA operates by design frequenzselektierend. The transfer function of the voltage gain is band-pass character. On the input side of a LNA in the field impedance of the antenna needs to be adjusted.