Filter bank circuit, spectrum analyzer, signal analyzer, signal generator using the same, and control method for the filter bank circuit

A filter bank circuit, comprising:

• a one-pole n-throw type switch that performs changeover among n output terminals connected to one input terminal, where n is an integer of 2 or more;
• and
• n filter groups respectively connected to the n output terminals, each of the filter groups having m filter circuits, where m is an integer of 2 or more;
• wherein each of the filter circuits in the n filter groups has a passband that does not overlap with a passband of any other filter circuit in the same filter group, and overlaps with a passband of one filter circuit in other one filter group by a predetermined bandwidth,
• wherein each of the n×m filter circuits comprises a circulator and a band-pass filter,
• wherein the circulator has an input port, an output port, and a transfer port, when a frequency component inputted to the input port is a frequency component corresponding to a passband of the each filter circuit, the circulator outputs the frequency component to the output port, and when the frequency component inputted to the input port is outside the passband, the circulator outputs the frequency component from the transfer port to an input port of the next stage, and
• wherein the band-pass filter is connected to the output port, and a passband of the band-pass filter is set according to the passband of the each filter circuit.