Designing methods and circuits for multi-band electronic circuits

A multi-band electronic circuit, comprising:

• a transistor;
• a first inductor electrically connected to the input terminal of said transistor;
• and
• a variable capacitance component electrically connected between said input terminal and the output terminal of said transistor,
• wherein, through changing the capacitance of said variable capacitance component, the resonant frequency of said electronic circuit is switched from a first band to a second band in response to said changed capacitance for switching among multiple bands, wherein each of said first band and said second band is one of a plurality of bands of said resonant frequency.

A multi-band electronic circuit, comprising:

• a first transistor having an input electrode, a first electrode electrically connected to a ground, and a second electrode;
• a first inductor electrically connected to said input electrode of said first transistor;
• a first resistor having one end electrically connected to said second electrode of said first transistor;
• a first power supply electrically connected to the other end of said first resistor;
• a capacitor having one end electrically connected to said second electrode of said first transistor;
• a second transistor having an input electrode electrically connected to the other end of said capacitor, a first electrode electrically connected to said ground and a second electrode;
• a second resistor having one end electrically connected to said second electrode of said second transistor;
• a second power supply electrically connected to the other end of said second resistor;
• a third resistor electrically connected between said input electrode and said second electrode of said second transistor;
• and
• a variable capacitance component electrically connected between said input electrode and said second electrode of said first transistor,
• wherein, through changing the capacitance of said variable capacitance component, the resonant frequency of the input impedance looking into said input electrode of said first transistor and said first inductor of said electronic circuit is switched from a first band to a second band in response to said changed capacitance for switching among multiple bands, wherein each of said first band and said second band is one of a plurality of bands of said resonant frequency.

A designing method for an electronic circuit of a multi-band amplifier, wherein said electronic circuit comprises at least one transistor having an input terminal and an inductor electrically connected to said input terminal of said at least one transistor, comprising steps of:

• changing a bias of said at least one transistor of said electronic circuit;
• and
• switching the resonant frequency of the input impedance of said at least one transistor and said inductor from a first band to a second band in response to said changed bias for switching among multiple bands,
• wherein each of said first band and said second band is one of a plurality of bands of said resonant frequency.

An electronic circuit for a multi-band amplifier, comprising:

• a first transistor having an input electrode, a first electrode electrically connected to a ground, and a second electrode;
• an inductor electrically connected to said input electrode of said first transistor;
• a first resistor having one end electrically connected to said second electrode of said first transistor;
• a first power supply electrically connected to one end of said first resistor;
• a capacitor having one end electrically connected to said second electrode of said first transistor;
• a second transistor having an input electrode electrically connected to the other end of said capacitor, a first electrode electrically connected to said ground, and a second electrode;
• a second resistor having one end electrically connected to said second electrode of said second transistor;
• a second power supply electrically connected to the other end of said second resistor;
• and
• a third resistor electrically connected between said input electrode and said second electrode of said second transistor,
• wherein, through changing a bias of said first transistor of said electronic circuit, the resonant frequency of the input impedance of said first transistor and said inductor of said electronic circuit is switched from a first band to a second band in response to said changed bias for switching among multiple bands, wherein each of said first band and said second band is one of a plurality of bands of said resonant frequency.