All wire-free communication applications require so-called low noise amplifiers (LNA) in order to amplify the input signal as far as possible without additional noise. Since ever higher frequencies are used in wire-free communication applications, it becomes necessary to adapt the low noise amplifiers in such a way that they are suitable for said higher frequencies. Furthermore, the power loss of the low noise amplifiers or of an entire receiver in which a low noise amplifier is incorporated should be kept as small as possible. Typical examples of low noise amplifiers are disclosed.
In order still to achieve a sufficient gain of the low noise amplifiers even at high frequencies, coils are usually used in the design of circuit layouts. Coils that are provided for such applications generally have high quality factors, as a result of which it becomes possible to use the relevantly equipped low noise amplifiers. One disadvantage of using coils, however, is that they usually lead to a low available bandwidth of the receiver, that is to say that, when using coils, increasing the quality factor of the low noise amplifier is accompanied by a reduction of the bandwidth available for the use of the low noise amplifier. It can happen in this case that the bandwidth of the low noise amplifier does not suffice to process the bandwidths required for present-day wire-free communication applications.
One possibility for compensating for this disadvantage is to provide a plurality of capacitances in the circuit layout which are connected in parallel with the coil and together with the latter form a resonant circuit. Said capacitances are typically embodied as so-called metal to metal capacitances (MIMCaps). By using such capacitances in low noise amplifiers, it is possible to increase the bandwidth of the signals which can be processed by the low noise amplifiers, but by the same token the quality factor of the low noise amplifiers is reduced in this case.
One possibility for shifting the center frequency, i.e., the resonant frequency, of such a resonant circuit is to use switches, e.g., transistors, which are connected in series with the MIMCaps. The transistors make it possible for individual ones of the capacitances incorporated to be connected and disconnected, as a result of which the resonant frequency, i.e., the center frequency, of the resonant circuit is varied, i.e., the resonant circuit is detuned. Such a detuneable low noise amplifier is disclosed, by way of example.
For these and other reasons, there is a need for the present invention, including providing an integrated amplifier, an electronic communication unit with integrated amplifier and a method for operating the electronic communication unit with integrated amplifier, the integrated amplifier having a smaller space requirement, compared with the low noise amplifiers known in the prior art.