Abstract: An analog circuit automatic calibration system for calibrating an object circuit that is an analog circuit having a characteristic changing with an input set value. The system includes: a set value storage section for storing a value and outputting the value to the object circuit as the set value; a characteristic detection section for detecting the characteristic of the object circuit; a first characteristic change section for determining the set value so that the characteristic of the object circuit is optimized; a second characteristic change section for updating the set value so that the characteristic of the object circuit is maintained, using an algorithm different from that used in the first characteristic change section; and a selector for selecting either one of the outputs of the first and second characteristic sections to enable the selected one to be stored in the set value storage section.

Abstract: The invention provides a low-pass filter suitably used as a loop filter for a PLL or a DLL that has a filtering characteristic equivalent to that of a conventional one and can be realized in a smaller circuit area. The low-pass filter includes first filtering means (31) for accepting, as an input, an input signal to the low-pass filter and outputting a first voltage; a circuit element (311) included in the first filtering means (31) for allowing a first current to flow in accordance with the first voltage; current generating means (32) for generating a second current at a given rate to the first current; second filtering means (33) for accepting, as an input, the second current and outputting a second voltage; and adding means (34) for adding the first voltage and the second voltage and outputting an output signal of the low-pass filter, in which the second current is set to be smaller than the first current.

Abstract: To realize an equivalence verification between an analog circuit and its function model unit. From a circuit topology and a functional description, there is extracted contained in the circuit. A test circuit capable of inputting a verification vector according to the extracted circuit function is created, and a verification is made to provide a result. In case the equivalence is to be verified, a similar verification is made by replacing only a compared circuit of the test circuit created. After the result was obtained, its difference from the aforementioned result is made. If this difference is within an allowable range, the equivalence is decided. By using the configuration of the invention, the analog circuit or the function model can be verified on itself. Moreover, the equivalence can be verified with the minimum configuration.

Abstract: In order to correct the duty cycle of a given clock signal to produce a clock signal with a 50% duty cycle, a duty cycle correction circuit includes a delay unit for delaying a first clock signal to output a second clock signal and a clock-signal output unit. The clock-signal output unit includes two transistors which use the first and second clock signals as the inputs of respective gates and an inverter circuit for inverting a signal output from a common drain of the transistors to output a third clock signal. The delay unit delays the first clock signal so that the first clock signal falling appears at a timing at which the duty cycle thereof becomes 50%. The two transistors in the clock-signal output unit output, as the third clock signal, a ground voltage and a source voltage as the signal from the common drain in response to the rising of the first clock signal and the falling of the second clock signal, respectively.

Abstract: The invention provides a low-pass filter suitably used as a loop filter for a PLL or a DLL that has a filtering characteristic equivalent to that of a conventional one and can be realized in a smaller circuit area. The low-pass filter includes first filtering means (31) for accepting, as an input, an input signal to the low-pass filter and outputting a first voltage; a circuit element (311) included in the first filtering means (31) for allowing a first current to flow in accordance with the first voltage; current generating means (32) for generating a second current at a given rate to the first current; second filtering means (33) for accepting, as an input, the second current and outputting a second voltage; and adding means (34) for adding the first voltage and the second voltage and outputting an output signal of the low-pass filter, in which the second current is set to be smaller than the first current.

Abstract: An analog circuit automatic calibration system for calibrating an object circuit that is an analog circuit having a characteristic changing with an input set value. The system includes: a set value storage section for storing a value and outputting the value to the object circuit as the set value; a characteristic detection section for detecting the characteristic of the object circuit; a first characteristic change section for determining the set value so that the characteristic of the object circuit is optimized; a second characteristic change section for updating the set value so that the characteristic of the object circuit is maintained, using an algorithm different from that used in the first characteristic change section; and a selector for selecting either one of the outputs of the first and second characteristic sections to enable the selected one to be stored in the set value storage section.

Abstract: In order to correct the duty cycle of a given clock signal to produce a clock signal with a 50% duty cycle, a duty cycle correction circuit includes a delay unit for delaying a first clock signal to output a second clock signal and a clock-signal output unit. The clock-signal output unit includes two transistors which use the first and second clock signals as the inputs of respective gates and an inverter circuit for inverting a signal output from a common drain of the transistors to output a third clock signal. The delay unit delays the first clock signal so that the first clock signal falling appears at a timing at which the duty cycle thereof becomes 50%. The two transistors in the clock-signal output unit output, as the third clock signal, a ground voltage and a source voltage as the signal from the common drain in response to the rising of the first clock signal and the falling of the second clock signal, respectively.

Abstract: A digital signal corresponding to each pixel of a liquid crystal display (LCD) is converted into an analog signal by a digital-to-analog (D-A) converting section. A CCD (Charge Coupled Device) delay line sequentially transfers the received analog signal according to a transfer clock signal. In response to a drive control signal, a signal output section receives the analog signal from the CCD delay line for output as a pixel signal of the LCD. The above structure eliminates the need to provide a multiplicity of D-A converters corresponding to the number of pixels per scanning line.