Abstract: In accordance with selection signals corresponding to an operation mode from a mode detection circuit, the voltage levels of back gate voltages applied to the back gates of MOS transistors included in internal circuitry are selected, by the selection signals, among the voltages from voltage generation circuits for generating a plurality of voltages having different voltage levels. The threshold voltage and the drive current of the MOS transistor are adjusted in accordance with the operation mode, and the semiconductor integrated circuit device which operates at high speed with low current consumption can be achieved.

Abstract: In accordance with selection signals corresponding to an operation mode from a mode detection circuit, the voltage levels of back gate voltages applied to the back gates of MOS transistors included in internal circuitry are selected, by the selection signals, among the voltages from voltage generation circuits for generating a plurality of voltages having different voltage levels. The threshold voltage and the drive current of the MOS transistor are adjusted in accordance with the operation mode, and the semiconductor integrated circuit device which operates at high speed with low current consumption can be achieved.

Abstract: An A/D-D/A converting apparatus, in which a multiplier is omitted by storing the multiplied result of a filter coefficient and a digital signal in advance and reading it out responsive to the inputted digital signal, in view of the point that filter characteristics of digital filters of an A/D converting unit and a D/A converting unit are equal one another, memories which are coefficient generating devices are used in common, and further, in view of the point :hat processing contents of respective digital filters are equal, a multiplier and an accumulator constituting the digital filter are used in common to reduce a circuit configuration considerably.

Abstract: A microprocessor, including a synchronous type memory having several parts, includes a power saving feature that places at least some parts of the memory in a non-operating state when instructions not requiring access to the memory are executed. An enable signal is generated when access is not required and a signal supplying circuit supplies a synchronous signal when the enable signal is not generated and supplies a signal in a predetermined state to place at least some parts or all parts of the memory in the non-operating state to reduce power consumption.

Abstract: A decimation type digital filter which utilizes the thinned-out signal of a finite impulse response (FIR) filter having N taps for processing the signal by the product sum operation of filter coefficients and the input signals inputted at every first period, in which, on the basis of the ratio K between a first period which is the input signal period and an output signal period and the number of taps N, M (a value obtained by raising below the decimal point of N/K) registers are provided and M successive output signals are processed by the product sum operation in parallel by respective registers, whereby the input signal is not necessarily to be held, a capacity of the register may be minimized and processing may be effected once for each register during the first period or by M number of times of product sum operation in total, thus the operating speed can be reduced to 1/K and the capacity and the operating speed can be optimized.

Abstract: A semiconductor integrated circuit of master and slave latches and the like that reduces power consumption by supplying a second clock which is a synchronous with a first clock to a slave latch only when the first clock that determines the latch period is supplied to a master latch, discontinuing the supply of the second clock after the master latch completes its latch action in the case that the supply of the first clock to the master latch is discontinued, and discontinuing the supply of clocks when latch action is not required, to reduce loads connected to them.

Abstract: A plurality sets of bit line pairs are connected to one set of common data line pair respectively through bit line selecting transistors. The common data line pair is coupled to the supply potential through precharging transistors. In the precharging period, a set of bit line pair is selected by a Y decoder to be connected to the common data line pair. On this occasion, the precharging transistor turns on in response to a precharge signal and the selected bit line pair is precharged through the common data line pair. The bit line pair which is not selected is not precharged.

Abstract: A memory circuit 14 comprises a MOS transistor 15 having its threshold voltage selected to be higher than the output voltage on the occasion of the ordinary operation. Consequently, the MOS transistor 15 is off on the occasion of the ordinary operation, and a ratio latch 4 performs the ordinary storing operation. Meanwhile, if the output voltage of the power source 12 is raised, the MOS transistor 15 turns on to pull down the potential of a data input line 6a to the ratio latch. Accordingly, the ratio latch 4 is forced to be set.