Abstract: A reference voltage generating circuit includes: a reference voltage generating circuit element including a first diode characteristic element and a second diode characteristic element, a density of a current flowing through the second diode characteristic element being different from a density of a current flowing through the first diode characteristic element, the reference voltage generating circuit element being configured to output a reference voltage generated based on a difference between voltages respectively applied to the first diode characteristic element and the second diode characteristic element; a first adjusting circuit element configured to adjust a first-order temperature coefficient of the reference voltage; and a second adjusting circuit element configured to adjust a second-order temperature coefficient of the reference voltage.

Abstract: The present invention provides a reference voltage generating circuit capable of improving a temperature dependence characteristic by a simple configuration. The reference voltage generating circuit includes: a reference voltage generating circuit element including a first diode characteristic element and a second diode characteristic element, a density of a current flowing through the second diode characteristic element being different from a density of a current flowing through the first diode characteristic element, the reference voltage generating circuit element being configured to output a reference voltage generated based on a difference between voltages respectively applied to the first diode characteristic element and the second diode characteristic element; a first adjusting circuit element configured to adjust a first-order temperature coefficient of the reference voltage; and a second adjusting circuit element configured to adjust a second-order temperature coefficient of the reference voltage.

Abstract: A MOS transistor including a first MOS transistor M1 to be used as a resistor; an input voltage source 1 connected to the source of the first MOS transistor for applying an input voltage Vin; and a gate voltage source 6 connected to the gate of the first MOS transistor for applying a gate voltage Vg. The gate voltage Vg and the input voltage Vin are set within a range where a gate-source voltage and source-drain voltage of the first MOS transistor cause the first MOS transistor to operate in a non-saturation region and also are set to avoid the first MOS transistor operating in an operation region with leakage current. Fluctuations of the resistance value resulting from a change in leakage current due to manufacturing variations are reduced and favorable temperature characteristics are obtained.

Abstract: Four input nodes I1-I4 for inputting 4-phase signals, four resistors R1-R4, four capacitors C1-C4, and four output nodes O1-O4 for outputting 4-phase signals are provided. The resistors and the capacitors are connected alternately in a loop, and the input nodes and output nodes are connected alternately to the respective nodes between the resistors and the capacitors sequentially. Each of the four resistors is composed of a group of three or more partial resistors, and three groups of the partial resistors R2a-R2c, R3a-R3c and R4a-R4c are collected respectively and arranged in the same attitude, while the partial resistors R1a-R1c of the remaining group are distributed into the other groups and arranged in the same line the same attitude as the partial resistors of each of the other groups. The regions of the thus collected groups are arranged in one direction.

Abstract: A current source apparatus includes a first MOS transistor having a drain serving as current input terminals with the gate connected to the drain, a first switch connected to the source of the first MOS transistor, a second MOS transistor having a drain serving as a current output terminal, a second switch connected to the source of the second MOS transistor, a third switch having one end connected to the gate of the first MOS transistor, and the other end connected to the gate of the second MOS transistor, and a drive circuit which controls the second switch and the third switch.

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: An intermediate-frequency signal from a frequency mixer is subjected to channel selection by a band-pass filter. Then an output signal from the band-pass filter is subjected to analog-to-digital conversion by an analog-to-digital converter on a predetermined sampling frequency. An anti-aliasing filter is provided at a stage previous to the analog-to-digital converter. The anti-aliasing filter includes notch filters and attenuates signals with frequencies which are higher and lower than a frequency which is an integral multiple of the sampling frequency by the intermediate frequency.

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: The receiver IF system or the signal selection device of the present invention includes: frequency converters that obtain polyphase intermediate-frequency signals for suppressing an image component of an RF signal from an input signal; a polyphase filter for removing an image component from the polyphase intermediate-frequency signals; and a band-pass filter composed of an N-pass filter for selecting a channel of an intermediate-frequency signal that is obtained by removing an image component from an output of the polyphase filter. An image rejection filter and a channel selection filter can be integrated at low cost with higher performance, and an area of a substrate for reception can be reduced.

Abstract: Four input nodes I1-I4 for inputting 4-phase signals, four resistors R1-R4, four capacitors C1-C4, and four output nodes O1-O4 for outputting 4-phase signals are provided. The resistors and the capacitors are connected alternately in a loop, and the input nodes and output nodes are connected alternately to the respective nodes between the resistors and the capacitors sequentially. Each of the four resistors is composed of a group of three or more partial resistors, and three groups of the partial resistors R2a-R2c, R3a-R3c and R4a-R4c are collected respectively and arranged in the same attitude, while the partial resistors R1a-R1c of the remaining group are distributed into the other groups and arranged in the same line the same attitude as the partial resistors of each of the other groups. The regions of the thus collected groups are arranged in one direction.

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: A first current mirror circuit that operates at the time of a rise in a first signal is connected to a current source, a second current mirror circuit that operates at the time of a rise in the first signal is connected to the first current mirror circuit, and a third current mirror circuit that operates at the time of a rise in a second signal is respectively connected to the current source and the point of connection between the first current mirror circuit and the second current mirror circuit. A pulse generation circuit for generating first and second signals from an external signal is provided. The second signal rises in sync with the first signal, and falls before the first signal.

Abstract: There is provided a current source circuit in which a outflow current of an output terminal is equal to an inflow current thereof. The current source circuit includes a first transistor group converting a reference current from a reference current source into a voltage and a first transistor having a current mirror relationship with the first transistor group, and allowing an output current to flow therethrough. An error amplifier compares a voltage generated in the first transistor group and supplied to one input terminal with a voltage supplied to the other input terminal. A second transistor is driven with an output voltage of the error amplifier. A third transistor is driven with the output voltage of the error amplifier, and allows an output current to flow therethrough in a direction opposite to the output current of the first transistor with respect to an output terminal.

Abstract: There is provided a current source circuit in which a outflow current of an output terminal is equal to an inflow current thereof. The current source circuit includes a first transistor group converting a reference current from a reference current source into a voltage and a first transistor having a current mirror relationship with the first transistor group, and allowing an output current to flow therethrough. An error amplifier compares a voltage generated in the first transistor group and supplied to one input terminal with a voltage supplied to the other input terminal. A second transistor is driven with an output voltage of the error amplifier. A third transistor is driven with the output voltage of the error amplifier, and allows an output current to flow therethrough in a direction opposite to the output current of the first transistor with respect to an output terminal.

Abstract: There is provided a current source circuit in which a outflow current of an output terminal is equal to an inflow current thereof. The current source circuit includes a first transistor group converting a reference current from a reference current source into a voltage and a first transistor having a current mirror relationship with the first transistor group, and allowing an output current to flow therethrough. An error amplifier compares a voltage generated in the first transistor group and supplied to one input terminal with a voltage supplied to the other input terminal. A second transistor is driven with an output voltage of the error amplifier. A third transistor is driven with the output voltage of the error amplifier, and allows an output current to flow therethrough in a direction opposite to the output current of the first transistor with respect to an output terminal.

Abstract: A first current mirror circuit that operates at the time of a rise in a first signal is connected to a current source, a second current mirror circuit that operates at the time of a rise in the first signal is connected to the first current mirror circuit, and a third current mirror circuit that operates at the time of a rise in a second signal is respectively connected to the current source and the point of connection between the first current mirror circuit and the second current mirror circuit. A pulse generation circuit for generating first and second signals from an external signal is provided. The second signal rises in sync with the first signal, and falls before the first signal.

Abstract: In a differential amplifier and an operational amplifier each for amplifying a signal, a differential signal composed of first and second signals is inputted to a couple of input terminals (1, 2). When the voltage of the first signal is, e.g., less than the voltage value of a reference voltage source (15), a comparator (13) senses it and a switch circuit (12) switches to a first current source (6) and a current from a third current source (11) flows into the first current source (6) so that a current is inhibited from flowing in the first differential couple (4). As a result, the inputted differential signal is amplified and outputted only through a second differential couple (5). In a situation in which the voltage of the first signal exceeds the voltage of the reference voltage source (15), on the other hand, the switch circuit (12) switches to a current source (7) so that the inputted differential signal is amplified and outputted only through the first differential couple (4).

Abstract: There is provided a current source circuit in which a outflow current of an output terminal is equal to an inflow current thereof. The current source circuit includes a first transistor group converting a reference current from a reference current source into a voltage and a first transistor having a current mirror relationship with the first transistor group, and allowing an output current to flow therethrough. An error amplifier compares a voltage generated in the first transistor group and supplied to one input terminal with a voltage supplied to the other input terminal. A second transistor is driven with an output voltage of the error amplifier. A third transistor is driven with the output voltage of the error amplifier, and allows an output current to flow therethrough in a direction opposite to the output current of the first transistor with respect to an output terminal.