Abstract: In a current switch circuit A used for a current steering D/A converter, a current switch basic circuit 1 includes first and second transistors Tr121 and Tr122 included in a differential switch 12. A threshold voltage control circuit 5 has an output terminal Vbout controlling the substrate voltage to be outputted to the substrate terminal of each of the two transistors Tr121 and Tr122 included in the differential switch 12 for controlling the threshold voltage of the two transistors of the differential switch. Accordingly, the present invention improves the decrease in the dynamic range of the current switch basic circuit 1 dependent on the threshold of each of the two transistors in the differential switch 12 and realizes a wider output voltage range without causing deterioration in properties even in a case that the power voltage is reduced in the current switch basic circuit 1.

Abstract: In a multi-channel current steering DA converter, e.g., a two-channel current steering DA converter, reference current sources Irefa and Irefb that can serve as current mirror sources for current sources Ia and Ib are provided in current source matrices 2a and 2b of the channels, respectively. During an operation, the reference current source Irefa or Irefb that is provided in the current source matrix of a channel that is not powered down is selected and used in accordance with control signals 6a and 6b. Therefore, even when one channel is powered down, the full-scale current of the other channel can be maintained at a constant value, i.e., unchanged.

Abstract: A D/A converter has a plurality of current sources (IS1, IS2, IS3-1 to IS3-63) including transistors and selects, according to a given digital signal, paths of the currents output from the current sources (IS1, IS2, IS3-1 to IS3-63), thereby converting the digital signal to an analog signal. In the D/A converter, a forward body bias voltage is applied to the back gate terminals of the transistors constituting each of the current sources (IS1, IS2, IS3-1 to IS3-63).

Abstract: A multi-channel current steering DAC (Digital-to-Analog Converter), for example, a 2-channel current steering DAC, includes a plurality of current sources I1, I2, . . . corresponding to the number of bits of a digital input signal DS in each of channels A, B. Each of the plurality of current sources I1, I2, . . . is formed by two small-current sources (I11, I12), (I21, I22), . . . . In the case where a full-scale current is limited to a small value in any of the channels, one of the two divided current sources is turned off by switches Sa1, Sa2. Accordingly, a full-scale current of each channel can be adjusted with a common bias circuit without degrading the resolution.

Abstract: When a semiconductor circuit, in which a stabilizing capacitor 2 for stabilizing a reference voltage Vbias is connected to a reference voltage terminal RT, recovers from a power down state to an operational state, a current mirror circuit 40 provides current mirroring of a current Ia of a first current path Ph1, which generates an OFF threshold voltage ref1 of a hysteresis comparator 1, to generate a current Ib of a second current path Ph2, which generates the reference voltage Vbias. The reference voltage Vbias is input to the comparator 1 as an input voltage vin. When the reference voltage Vbias becomes equal to the OFF threshold voltage ref1, the comparator 1 immediately stops the charging of the stabilizing capacitor 2 by a current source I1.

Abstract: In a current steering D/A converter, a 1LSB current source 1 and a 2LSB current source 2 are binary code current sources for outputting currents with current values weighted by ½, and a 4LSB current source 3 is one of a large number of current sources designed as thermometer code current source with the same structure. In first circuits A1, A2 and A4 for respectively determining constant current values of the current sources 1 through 3, a plurality of MOS transistors with a channel length L3 and a channel width W3 are cascode-connected to one another with gate terminals thereof shared. In second circuits B1, B2 and B4 respectively used for setting high output impedance of the current sources 1 through 3, a plurality of MOS transistors with a channel length L4 and a channel width W4 are cascode-connected to one another with gate terminals thereof shared.

Abstract: In an analog video signal generation circuit, an inverting output terminal NDAOUT4 of a first current-steering differential-output D/A converter DAC4 and an inverting output terminal NDAOUT5 of a second current-steering differential-output D/A converter DAC5 are connected together, and the connection point thereof is connected to a current-to-voltage converter RL6 and to the input terminal of an inverting amplifier AMP. The output terminal of the inverting amplifier AMP is connected with a first video signal output terminal COMPout. This structure uses no adders and thus can reduce the price of video equipment, while using the current-steering differential-output D/A converters DAC4 and DAC5 so that currents consumed by the D/A converters are used effectively. Thus, the avoidance of the use of adders allows the component cost to be reduced, while the effective use of currents consumed in the current-steering D/A converters leads to reduction in power consumption.

Abstract: In a multi-channel current steering DA converter, e.g., a two-channel current steering DA converter, reference current sources Irefa and Irefb that can serve as current mirror sources for current sources Ia and Ib are provided in current source matrices 2a and 2b of the channels, respectively. During an operation, the reference current source Irefa or Irefb that is provided in the current source matrix of a channel that is not powered down is selected and used in accordance with control signals 6a and 6b. Therefore, even when one channel is powered down, the full-scale current of the other channel can be maintained at a constant value, i.e., unchanged.

Abstract: [Means for Solving the Problem] In a current switch circuit A used for a current steering D/A converter, a current switch basic circuit 1 includes first and second transistors Tr121 and Tr122 included in a differential switch 12. A threshold voltage control circuit 5 has an output terminal Vbout controlling the substrate voltage to be outputted to the substrate terminal of each of the two transistors Tr121 and Tr122 included in the differential switch 12 for controlling the threshold voltage of the two transistors of the differential switch. Accordingly, the present invention improves the decrease in the dynamic range of the current switch basic circuit 1 dependent on the threshold of each of the two transistors in the differential switch 12 and realizes a wider output voltage range without causing deterioration in properties even in a case that the power voltage is reduced in the current switch basic circuit 1.

Abstract: A multi-channel current steering DAC (Digital-to-Analog Converter), for example, a 2-channel current steering DAC, includes a plurality of current sources I1, I2, . . . corresponding to the number of bits of a digital input signal DS in each of channels A, B. Each of the plurality of current sources I1, I2, . . . is formed by two small-current sources (I11, I12), (I21, I22), . . . . In the case where a full-scale current is limited to a small value in any of the channels, one of the two divided current sources is turned off by switches Sa1, Sa2. Accordingly, a full-scale current of each channel can be adjusted with a common bias circuit without degrading the resolution.

Abstract: A semiconductor integrated circuit is provided with a reference voltage generation circuit for generating a voltage to be a reference, a function circuit that is operated using an output voltage of the reference voltage generation circuit, and a reference voltage stabilization capacitor for stabilizing the output voltage, which is connected to an output terminal of the reference voltage generation circuit. During standby, the function circuit stops operating while the reference voltage generation circuit continues operating to prevent discharging of the reference voltage stabilization capacitor, thereby realizing reduction in power consumption of the function circuit such as an analog circuit as well as high-speed recovery from the standby state to the normal operation state.

Abstract: A current output type D/A converter for converting a digital signal into an analog signal comprises a control signal input terminal for receiving a control signal supplied from the outside, and an output load element having a switching mechanism for electrically connecting or disconnecting the output load element to/from an analog output node on the basis of the control signal applied to the control input terminal.

Abstract: A current output type D/A converter for converting a digital signal into an analog signal comprises a control signal input terminal for receiving a control signal supplied from the outside, and an output load element having a switching mechanism for electrically connecting or disconnecting the output load element to/from an analog output node on the basis of the control signal applied to the control input terminal.

Abstract: A semiconductor integrated circuit is provided with a reference voltage generation circuit for generating a voltage to be a reference, a function circuit that is operated using an output voltage of the reference voltage generation circuit, and a reference voltage stabilization capacitor for stabilizing the output voltage, which is connected to an output terminal of the reference voltage generation circuit. During standby, the function circuit stops operating while the reference voltage generation circuit continues operating to prevent discharging of the reference voltage stabilization capacitor, thereby realizing reduction in power consumption of the function circuit such as an analog circuit as well as high-speed recovery from the standby state to the normal operation state.

Abstract: In a CMOS level shifting circuit including N-channel transistors that have sources to which a digital signal is supplied, a bias voltage Vref is supplied to gates of the N-channel transistors, and the bias voltage Vref is set to be higher than a high level voltage of the digital signal and lower than a value obtained by adding a threshold voltage of the N-channel transistors to the high level voltage of the digital signal. Thus, a level shifting circuit is provided that is capable of outputting a signal having subjected to stable level conversion, even when a voltage level of a low voltage signal is lowered.

Abstract: When the performance of an A/D converter required by a system changes, power consumption of the overall system can be reduced. The resolution of an A/D converter is made variable by changing a current flowing through an amplifier by an external control signal that specifies the resolution. Thus, when the performance required by a system changes, it is possible to change the performance of the A/D converter and to prevent a performance overhead of the A/D converter. Consequently, power consumption of the A/D converter is reduced, and power consumption of the system as a whole is also reduced.

Abstract: When the performance of an A/D converter required by a system changes, power consumption of the overall system can be reduced. The resolution of an A/D converter is made variable by changing a current flowing through an amplifier by an external control signal that specifies the resolution. Thus, when the performance required by a system changes, it is possible to change the performance of the A/D converter and to prevent a performance overhead of the A/D converter. Consequently, power consumption of the A/D converter is reduced, and power consumption of the system as a whole is also reduced.

Abstract: A current steering type D/A converter comprises a D/A conversion circuit having plural current sources each outputting a predetermined current, and a logic circuit for selecting desired current sources from among the plural current sources; a reference voltage generation circuit for generating a reference voltage potential that determines an output current value of the D/A conversion circuit; and a control circuit for setting the D/A conversion circuit in the ON state or OFF state by controlling switch elements which are placed between the D/A conversion circuit and the reference voltage generation circuit. Therefore, current consumption of the current steering type D/A converter can be reduced.

Abstract: In a CMOS level shifting circuit including N-channel transistors that have sources to which a digital signal is supplied, a bias voltage Vref is supplied to gates of the N-channel transistors, and the bias voltage Vref is set to be higher than a high level voltage of the digital signal and lower than a value obtained by adding a threshold voltage of the N-channel transistors to the high level voltage of the digital signal. Thus, a level shifting circuit is provided that is capable of outputting a signal having subjected to stable level conversion, even when a voltage level of a low voltage signal is lowered.

Abstract: A current steering type D/A converter comprises a D/A conversion circuit having plural current sources each outputting a predetermined current, and a logic circuit for selecting desired current sources from among the plural current sources; a reference voltage generation circuit for generating a reference voltage potential that determines an output current value of the D/A conversion circuit; and a control circuit for setting the D/A conversion circuit in the ON state or OFF state by controlling switch elements which are placed between the D/A conversion circuit and the reference voltage generation circuit. Therefore, current consumption of the current steering type D/A converter can be reduced.