Abstract:
In a time-to-digital conversion stage, a time-to-digital conversion circuit outputs an n-bit digital signal, which represents an integer value ranging from −(2n-1−1) to +(2n-1−1), based on a phase difference between a first and a second signals input thereto; a time difference amplifier circuit amplifies the phase difference between the first and the second signals 2n-1 times, and outputs two signals having an amplified phase difference therebetween; a delay adjustment circuit adds a phase difference dependent on the digital signal to the two signals output from the time difference amplifier circuit, and outputs another two signals; an output detection circuit detects that the delay adjustment circuit has output the another two signals, and outputs a detection signal; and a storage circuit latches the digital signal in synchronism with the detection signal. Multi-stage coupling of the time-to-digital conversion stages forms a pipeline time-to-digital converter.
Abstract:
A high order integrator is configured using an operational amplifier, a first filter connected between an input terminal of the integrator and an inverted input terminal of the operational amplifier, and a second filter connected between the inverted input terminal and output terminal of the operational amplifier. The first filter includes n serially-connected first resistance elements, n−1 first capacitance elements each connected between each interconnecting node of the first resistance elements and the ground, and n−1 second resistance elements each connected between each interconnecting node of the first resistance elements and the ground. The second filter includes n serially-connected second capacitance elements, n−1 third resistance elements each connected between each interconnecting node of the second capacitance elements and the ground, and n−1 third capacitance elements each connected between each interconnecting node of the second capacitance elements and the ground.
Abstract:
An oversampling A/D converter with a few operational amplifiers is configured using a complex second-order integrator including first and second second-order integrators and first and second coupling circuits configured to couple these integrators together. Each of the second-order integrators includes an operational amplifier, four resistance elements, and three capacitance elements. The first coupling circuit cross-couples one of two serially-connected capacitance elements inserted between the inverted input terminal and output terminal of the operational amplifier in the first second-order integrator to the counterpart in the second second-order integrator using two resistance elements. The second coupling circuit cross-couples the other capacitance element in the first second-order integrator to the counterpart in the second second-order integrator using two resistance elements.
Abstract:
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.
Abstract:
In a flash A/D converter, a predictor predicts next analog input data based on a digital output signal from an A/D converter, and outputs prediction data. Based on the prediction data from the predictor, a controller turns on comparators having reference voltages near the prediction data, and in order to ensure a certain degree of A/D conversion accuracy even when the prediction fails, also turns on even-numbered comparators 103.2a (where a is 0 to 7), for example. In this manner, even when prediction of next analog input data fails, a 4-bit A/D converter can perform A/D conversion with 3-bit accuracy, while saving power consumption by reducing the number of comparators to be turned on.
Abstract:
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.
Abstract:
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.
Abstract:
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.
Abstract:
In a filter adjustment circuit for an analog filter circuit such as a Gm-C filter, an input signal IS from a reference signal generation circuit 1 is inputted to a Gm-C filter 2 to be filtered and then converted by a conversion circuit 3 to a digital signal. A reference signal RS from the reference signal generation circuit 1 is converted by a conversion circuit 4 to a digital signal. The two converted signals are held in time series in a holding circuit 5. A timing generation circuit 6 generates an update timing signal en based on a reference time-series signal ref from the holding circuit 5. A control signal generation circuit 7 generates a control signal CS based on the reference time-series signal ref and a filter output time-series signal tgt, each from the holding circuit 5. The control signal CS is inputted to the Gm-C filter 2 in response to the update timing signal en to adjust the gain of the Gm-C filter 2. As a result, variations in the response characteristics of the Gm-C filter 2 are adjusted with high accuracy with a simple circuit structure.
Abstract:
A time required for an output voltage of a source follower to rise from Low to a predetermined voltage depends on a bias voltage. Therefore, by setting a converged voltage of an output voltage to be high by increasing the bias voltage, the time required to rise up to the predetermined voltage can be reduced. Therefore, a first source follower which is biased so that the converged value of the output voltage becomes a predetermined Hi voltage when an input data signal goes from Low to Hi, and a second source follower which is biased so as to become the Hi voltage after a period of one clock when an input data signal goes from Low to Hi, are used. The two source followers are operated with appropriate timing.