Distributed amplifier

A distributed amplifier comprising:

• N amplifier blocks, where N is an integer of 2 or more, each of the amplifier blocks including:
• a first transmission line having an input end that receives input of a signal,
• a second transmission line having an output end that outputs a signal,
• a first termination resistor having a first end connected to a terminal end of the first transmission line,
• a second termination resistor having a first end connected to an input end of the second transmission line, and
• a plurality of unit cells arranged along the first and second transmission lines, each of the unit cells having an input terminal connected to the first transmission line and an output terminal connected to the second transmission line, wherein:
• the amplifier blocks are connected in cascade such that a terminal end of the second transmission line of one of the amplifier blocks is connected to the input end of the first transmission line of a subsequent amplifier block,
• a second end of the first termination resistor of each of the amplifier blocks is connected to a first bias voltage, and a second end of the second termination resistor of each of the amplifier blocks is connected to a ground,
• values of the first transmission line of the amplifier block in a first stage, the first termination resistor of the amplifier block in the first stage, the characteristic impedance of the second transmission line of the amplifier block in a last stage, and the second termination resistor of the amplifier block in the last stage are 50Ω, and
• the characteristic impedance of the second transmission line of the amplifier block in an n-th stage, the second termination resistor of the amplifier block in the n-th stage, the characteristic impedance of the first transmission line of the amplifier block in an (n+1)-th stage, and the first termination resistor of the amplifier block in the (n+1)-th stage are set to −Vb_(n+1)/(Iopt×Nopt), where n is an integer from 1 to N−1, Vb_(n+1) is the first bias voltage of the amplifier block in the (n+1)-th stage, Nopt is the number of the unit cells in each of the amplifier blocks, and Iopt is the current that flows between the input terminal and the output terminal in each of the unit cells.

A distributed amplifier comprising:

• N amplifier blocks, where N is an integer of 2 or more, each of the amplifier blocks including:
• a first transmission line having an input end that receives input of a signal,
• a second transmission line having an output end that outputs a signal,
• a first termination resistor having a first end connected to a terminal end of the first transmission line,
• a second termination resistor having a first end connected to an input end of the second transmission line, and
• a plurality of unit cells arranged along the first and second transmission lines, each of the unit cells having an input terminal connected to the first transmission line and an output terminal connected to the second transmission line, wherein:
• the amplifier blocks are connected in cascade such that a terminal end of the second transmission line of one of the amplifier blocks is connected to the input end of the first transmission line of a subsequent amplifier block,
• a second end of the first termination resistor of each of the amplifier blocks is connected to a first bias voltage, and a second end of the second termination resistor of each of the amplifier blocks is connected to a ground,
• the values of the characteristic impedances of all the transmission lines and all the first and second termination resistors are 50Ω, and
• a transistor whose optimal current is −Vb_(n+1)/(Nopt_n×50) is used in each of the unit cells of the amplifier block in the n-th stage, where n is an integer from 1 to N−1, Vb_(n+1) is the first bias voltage of the amplifier block in the (n+1)-th stage, and Nopt_n is the number of the unit cells of the amplifier block in the n-th stage.