Switching circuit, signal output device and test apparatus
View Patent ↗A signal output device that outputs an output signal according to an input signal expressing a logical value that includes a high-voltage side switching circuit between a first terminal and a second terminal in accordance with a first control signal. The device includes a low-voltage side switching circuit between a first and second terminal for outputting a low-voltage side reference voltage in accordance with a second control signal and a control section. The high-voltage and low-voltage side switching circuits include a plurality of switching devices serially connected between the first terminal and the second terminal and each of which is opened in accordance with a provided control voltage. The control circuit opens the plurality of switching devices substantially in synchronization with each other, where a voltage inputted to the first terminal is outputted from the second terminal by short-circuiting between the first terminal and the second terminal.
1. A signal output device that outputs an output signal according to an input signal expressing a logical value, the signal output device comprising:
an output port that outputs the output signal;
a high-voltage side switching circuit that opens or short-circuits between a first terminal connected to a high-voltage side reference voltage generating port for outputting a high-voltage side reference voltage and a second terminal connected to the output port in accordance with a first control signal;
a low-voltage side switching circuit that opens or short-circuits between a first terminal connected to the output port and a second terminal connected to a low-voltage side reference voltage generating port for outputting a low-voltage side reference voltage lower than the high-voltage side reference voltage in accordance with a second control signal; and
a control section that outputs the first control signal and the second control signal according to the input signal causing the high-voltage side switching circuit to be opened when the low-voltage side switching circuit is being short-circuited and causing the low-voltage side switching circuit to be opened when the high-voltage side switching circuit is being short-circuited, and
each of the high-voltage side switching circuit and the low-voltage side switching circuit comprising:
a plurality of switching devices that is serially connected between the first terminal and the second terminal and each of which is opened or short-circuited in accordance with a provided control voltage; and
control circuit that is provided corresponding to the plurality of switching devices, which provides a control voltage according to the control signal to the corresponding switching device, and that opens and short-circuits the plurality of switching devices substantially in synchronization with each other, wherein a voltage inputted to the first terminal is outputted from the second terminal by short-circuiting between the first terminal and the second terminal.
2. The signal output device as claimed in claim 1 , wherein each of the plurality of switching devices has a withstand voltage smaller than a potential difference between the high-voltage side reference voltage and the low-voltage side reference voltage.
3. The signal output device as claimed in claim 1 , wherein the control section outputs a first and a second control signals making it go through a state where the low-voltage aide switching circuit is opened and the high-voltage side switching circuit is opened, when it transits from a state where the low-voltage side switching circuit is short-circuited and the high-voltage side switching circuit is opened to a state where the low-voltage side switching circuit is opened and the high-voltage side switching circuit is short-circuited or when it transits from the state where the low-voltage side switching circuit is opened and the high-voltage side switching circuit is short-circuited to the state where the low-voltage side switching circuit is short-circuited and the high-voltage side switching circuit is opened.
4. The signal output device as claimed in claim 1 , further comprising:
a pulse width modulating section that outputs the input signal obtained by pulse-width modulating a provided input value; and
a low-pass filter that outputs a signal obtained by low-pass filtering a voltage of the output port to an outside as the output signal.
5. The signal output device as claimed in claim 1 , wherein
the plurality of control circuits is provided one-to-one corresponding to the plurality of switching devices, and
each of the plurality of control circuits operates so that a delay time from a change of the control signal to providing the control voltage according to the after-change control signal to the corresponding switching device is shorter than a switching time from a change of the control voltage provided to the switching device to finishing a transition of a switching state of the switching device in accordance with this change of the control voltage.
6. The signal output device as claimed in claim 5 , wherein
each of the plurality of control circuits has a driving section that provides a first driving voltage or a second driving voltage to the switching device as the control voltage in accordance with the control signal, and
the driving section operates so that a change time changing the control voltage from the first driving voltage to the second driving voltage is shorter than the switching time of the switching device.
7. The signal output device as claimed in claim 6 , wherein each of the plurality of control circuits further has a signal insulating section that insulates the driving section from a circuit for outputting the control signal.