Partially complex modulated filter bank

Apparatus for processing a plurality of complex-valued subband signals, the plurality of complex-valued subband signals comprising a first complex-valued subband signal and a second complex-valued subband signal to obtain a real-valued subband signal, comprising:

• an extractor for extracting from the first complex-valued subband signal a first imaginary part, for extracting from the second complex-valued subband signal a second imaginary part and for extracting from the first, the second or a third complex-valued subband signal of the plurality of complex-valued subband signals a real part;
• a multiband filter for providing a real-valued intermediate subband signal by filtering the first imaginary part to obtain a first filtered imaginary part signal, by filtering the second imaginary part to obtain a second filtered imaginary part signal and by combining the first filtered imaginary part signal and the second filtered imaginary part signal to obtain the intermediate subband signal;
• a calculator for providing the real-valued subband signal by combining the real part and the intermediate signal;
• and
• a delayer for delaying the real part signal and for passing on the real part signal to the multiband filter in a delayed form.

Method for processing a plurality of real-valued subband signals, the plurality of real-valued subband signals comprising a first real-valued subband signal and a second real-valued subband signal to obtain a complex-valued subband signal, comprising:

• filtering, by a multiband filter, the first real-valued subband signal to obtain a first filtered subband signal and the second real-valued subband signal to obtain a second filtered subband signal;
• combining the first filtered subband signal and the second filtered subband signal when deriving a real-valued intermediate subband signal;
• combining, by a calculator, a real-valued subband signal from the plurality of real-valued subband signals as a real part of a complex-valued subband signal and a signal which is based on the intermediate subband signal as an imaginary part of the complex-valued subband signal;
• and
• delaying, by a delayer, the real-valued subband signal and providing the real-valued subband signal to the calculator in a delayed form.

Method for processing a plurality of complex-valued subband signals, the plurality of complex-valued subband signals comprising a first complex-valued subband signal and a second complex-valued subband signal to obtain a real-valued subband signal, comprising:

• extracting, by an extractor, from the first complex-valued subband signal a first imaginary part from the second complex-valued subband signal a second imaginary part and
• from the first, the second or a third complex-valued subband signal of the plurality of complex-valued subband signals a real part;
• filtering, by a multiband filter, the first imaginary part to obtain a first filtered imaginary part signal and the second imaginary part to obtain a second filtered imaginary part signal;
• combining the first filtered imaginary part signal and the second filtered imaginary part signal to obtain an intermediate subband signal;
• combining, by a calculator, the real part and the intermediate subband signal to obtain the real-valued signal the real-valued signal, and
• delaying, by a delayer, the real part signal and passing on the real part signal to the multiband filter in a delayed form.