Abstract: An amplifier typically exemplified by a TIA is realized that provides an optimal band characteristic, that reduces the possibility of the oscillation, and that achieves a reduced dispersion of the band characteristics. An amplifier for amplifying an electric signal, comprising: a first buffer for amplifying the electric signal; a filter that is connected to an output of the first buffer and that includes a parallel circuit consisting of an inductor and a first capacity; and a second buffer connected to an output of the filter.

Abstract: A driver circuit 11 includes a plurality of cascode-connected NMOS transistors, a modulating signal VGN1 is applied to a gate terminal of a lowermost stage transistor TN1 located at a lowermost stage out of the NMOS transistors, and an upper stage bias potential VGN2 that is a sum of a minimum gate-source voltage VGN1min and a maximum drain-source voltage VDS1max of a transistor (TN1) located immediately below an upper stage transistor located at an upper stage above the lowermost stage transistor of the NMOS transistors is applied to the upper stage transistor TN2.

Abstract: A positive-side power supply terminal (1-1a) of a differential amplifier (1-1) is connected to a positive-side power supply line (L1). A negative-side power supply terminal (1-2b) of a differential amplifier (1-2) is connected to a negative-side power supply line (L2). A negative-side power supply terminal (1-1b) of the differential amplifier (1-1) and a positive-side power supply terminal (1-2a) of the differential amplifier (1-2) are connected to each other. A final-stage amplifier (2) is connected between the positive-side power supply line (L1) and the negative-side power supply line (L2).

Abstract: A content server (10) includes a receiving unit (14) that receives a request signal from a request source terminal, an acquisition unit (15) that acquires an IP address assigned to the request source terminal from the request signal, and a determination unit (16) that determines a location region of a user of the request source terminal by referring to an address storage unit (11) based on the acquired IP address. The address storage unit (11) stores address information including location regions of registered users set based on addresses of the registered users and IP addresses assigned to terminals of the registered users in association with each other.

Abstract: A content server (10) includes a receiving unit (14) that receives a request signal from a request source terminal, an acquisition unit (15) that acquires an IP address assigned to the request source terminal from the request signal, and a determination unit (16) that determines a location region of a user of the request source terminal by referring to an address storage unit (11) based on the acquired IP address. The address storage unit (11) stores address information including location regions of registered users set based on addresses of the registered users and IP addresses assigned to terminals of the registered users in association with each other.