摘要:
In an interpolative modulator, a signal which varies by only .+-.1 with one clock from a 1-bit quantizer is used as a shift-direction control signal. The shift-direction control signal is given to a bidirectional shift register. The bidirectional shift register shifts data based on the value of the shift-direction control signal that has been received. The output from the bidirectional shift register is given as a control signal to a resistive-ladder-type D/A converter. The resistive-ladder-type D/A converter outputs an analog potential corresponding to a switch selected by the above control signal. Therefore, if a delay difference occurs between any two bits, two adjacent switches are simply selected simultaneously, so that the output from the resistive-ladder-type D/A converter varies continuously. Consequently, there can be provided an oversampling D/A converter of resistive-ladder type with high accuracy and an increased yield, which is free from glitch (transiently generated noise).
摘要:
The present invention provides a first-order delta-sigma AD converter adapted to conduct noise shaping and having a quantizer arranged such that, when the amplitude of an input signal entered into the quantizer is small, the amplitude of a difference signal between the input signal entered into the quantizer and an output signal therefrom, is small. It is therefore possible to achieve an efficient AD- or DA-converter reduced in power consumption, which satisfies the transmission characteristics of the specifications of CCITT G.714 based on a method of PCM-encoding an audio frequency band signal stipulated in the specifications of CCITT G.711.
摘要:
A reference voltage output terminal of first and second reference voltage generating circuits is connected to a first current input terminal of a current mirror circuit of an operational amplifier by a diode element. At the time of start-up, a reference voltage generated on the reference voltage output terminal is 0 V. Consequently, a current flows to the diode element and an offset voltage Voff is generated on the operational amplifier so that a malfunction point is caused to disappear. Accordingly, in the case where a normal operation point on which a reference voltage having an expected value is generated and a malfunction point on which an operation is stabilized with a reference voltage having a value less than the expected value are present, the generated reference voltage is raised at the time of start-up, passes through the malfunction point to reach an expected voltage value on the normal operation point and becomes stabilized. In this state, the diode element is cut off so that the offset voltage Voff is caused to disappear.
摘要:
A frequency-voltage conversion circuit 21 receives a clock CLK as an input and provides a voltage IVdd in accordance with the frequency of the clock as an output. The input and output characteristic of the frequency-voltage conversion circuit 21 is adjusted to substantially match a given input and output characteristic.
摘要:
Each of n level shifters (LS0 to LS7) includes an NMOS transistor (Mn1) for receiving any one of n clock signals (P0 to P7) and a PMOS transistor (Mp1) for receiving an output signal from another level shifter. An output signal given to the PMOS transistor (Mp1) included in each of the level shifters (LS0 to LS7) is an output signal of the level shifter which receives the clock signal whose phase delay amount with respect to the clock signal given to the NMOS transistor (Mn1) included in that level shifter is a phase amount X (0°
摘要:
Each of n level shifters (LS0 to LS7) includes an NMOS transistor (Mn1) for receiving any one of n clock signals (P0 to P7) and a PMOS transistor (Mp1) for receiving an output signal from another level shifter. An output signal given to the PMOS transistor (Mp1) included in each of the level shifters (LS0 to LS7) is an output signal of the level shifter which receives the clock signal whose phase delay amount with respect to the clock signal given to the NMOS transistor (Mn1) included in that level shifter is a phase amount X (0°
摘要:
A high-level period of each of n first pulse signals partially or wholly overlaps a period during which all of n second pulse signals are at the low level. A high-level period of each of the n second pulse signals partially or wholly overlaps a period during which all of the n first pulse signals are at the low level. Each of n first drive transistors includes a source connected to a ground node, a drain connected to a first node, and a gate receiving a corresponding one of the first pulse signals. Each of n second drive transistors includes a source connected to the ground node, a drain connected to a second node, and a gate receiving a corresponding one of the second pulse signals. A current mirror circuit allows a current corresponding to a current flowing through the second node to flow through the first node.
摘要:
A coupled ring oscillator includes n ring oscillators (20) each including m inverter circuits (10), and a phase-coupling loop (40) in which m×n phase-coupling circuits (30), each of which couples signal phases at two points in a certain phase mode, are connected with each other to form a loop. Connection points at which the inverter circuits (10) are connected with each other and the connection points at which the phase-coupling circuits (30) are connected with each other are connected bijectively; and each of the inverter circuits (10) is connected between two points that divide the phase-coupling circuits (30) into two parts at a certain ratio.
摘要:
An A/D converter includes: a plurality of A/D conversion circuits (10 a, 10b); an input selection section (20) for selecting the A/D conversion circuit that is not executing A/D conversion to supply analog amounts obtained by sample-holding an input signal; and an output selection section (30) for selecting the A/D conversion circuit that is not executing A/D conversion to output digital amounts obtained from the selected one. Each A/D conversion circuit includes: an input memory portion (11) for sequentially storing the supplied analog amounts in a plurality of analog memory elements (111); an A/D conversion portion (12) having a plurality of A/D conversion elements (121) for converting the analog amounts stored in the analog memory elements to digital amounts; and a shift output portion (13), having a plurality of registers (131) receiving the digital amounts from the A/D conversion elements to hold the digital amounts, for shifting and outputting the digital amounts held in the registers.
摘要:
A charge pumping circuit includes a first switch for controlling one of push and pull operations in accordance with a first control signal; a current mirror circuit constructed from transistors each having a different polarity from the first switch; a second switch for controlling current input to the current mirror circuit in accordance with a second control signal, the second switch being constructed from a transistor having the same characteristic as a transistor used for constructing the first switch; a first MOS capacitor one end of which is connected to an input side of the current mirror circuit; a second MOS capacitor receiving, at one end thereof, a current concerned with the push and pull operations; and a voltage buffer connected to the first and second MOS capacitors. The other of the push and pull operations is performed with an output current of the current mirror circuit.