Abstract: The PWM modulation circuit according to the invention is connected to an input terminal for an analog baseband signal and a staircase generating circuit generating a staircase wave, and carries out PWM modulation to a staircase wave input from the staircase generating circuit based on an analog baseband signal input from the input terminal. The staircase generating circuit includes a plurality of constant current source circuits, a plurality of switches connected to the plurality of constant current source circuits on a one-to-one basis, a serial-parallel conversion circuit that carries out serial-parallel conversion to a clock signal input from a clock signal input terminal and outputs the result to the plurality of switches, and an output voltage control circuit that converts a constant current input from the plurality of constant current source circuits into a constant voltage at an arbitrary value and outputs the result.

Abstract: A first semiconductor chip (1) of a high withstand voltage and a second semiconductor chip (2) of a low withstand voltage are connected to each other in a package (3). The first semiconductor chip (1) has a voltage conversion circuit (4), a plurality of first inter-chip connection portions (10) for connection to the second semiconductor chip (2), a first serial decoder (6), and external connection portions (13) for connection to the external connection terminals (12) led out of the package (3). The second semiconductor chip (2) has a second serial decoder (5) and a plurality of second inter-chip connection portions (11) for connection to the first semiconductor chip (1). Bonding wires (9) are provided which directly connect the plurality of first inter-chip connection portions (10) and the plurality of second inter-chip connection portions (11) to each other.

Abstract: The PWM modulation circuit according to the invention is connected to an input terminal for an analog baseband signal and a staircase generating circuit generating a staircase wave, and carries out PWM modulation to a staircase wave input from the staircase generating circuit based on an analog baseband signal input from the input terminal. The staircase generating circuit includes a plurality of constant current source circuits, a plurality of switches connected to the plurality of constant current source circuits on a one-to-one basis, a serial-parallel conversion circuit that carries out serial-parallel conversion to a clock signal input from a clock signal input terminal and outputs the result to the plurality of switches, and an output voltage control circuit that converts a constant current input from the plurality of constant current source circuits into a constant voltage at an arbitrary value and outputs the result.