Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Daisuke Nomasaki

Koji Oka

Kenji Murata

Toshiaki Ozeki

Yoshinori Miyada

Heiji Ikoma

Hideki Tanaka

Junichi Naka

Yoshitsugu Inagaki

Yoshikazu Makabe

Ikuo Hidaka

Youichi Okamoto

Hiroshi Sakura

An A/D converter which converts an analog input signal into a digital output signal by performing time-divisional parallel processings on the analog input signal using first and second pipeline type unit A/D converters. The A/D converter sets plural unit A/D converters performing parallel processings according to a system request, such that, when the A/D converter operates with a conversion frequency that is lower than the maximum conversion frequency, the unit A/D converter is halted by a control signal, thereby reducing inter-channel errors among the unit A/D converters to improve the precision of the A/D converter.

A/D converter and A/D conversion method

A differential voltage interconnect (W) electrically connects the gate electrode of a transistor to be used among differential transistors (T, T, . . . ) to an input node receiving an input voltage (Vinn), and a differential voltage interconnect (W) electrically connects the gate electrode of a transistor to be used among differential transistors (T, T, . . . ) to an input node receiving an input voltage (Vinp). A bias voltage interconnect (W) electrically connects the gate electrode of a transistor to be used among current source transistors (T, T, . . . ) to a bias node receiving a bias voltage (VBN), and a bias voltage interconnect (W) electrically connects the gate electrodes of transistors to be used among load transistors (T, T, . . . , T, T, . . . ) to a bias node receiving a bias voltage (VBP).

Operational amplifier and pipeline AD converter

In an A/D converter provided with an A/D converter circuitfor operationally amplifying an input signal and outputting an amplified signal, the A/D converter circuitincludes an initial value setting circuitin addition to an amplifier, a sub-A/D converter, a sub-D/A converterand capacitors Cand C. To ensure that the initial value of the output voltage of the amplifieris a given voltage value close to the target value of operational amplification at the start of the operational amplification by the amplifier, the initial value setting circuitapplies a given bias value equal to the given voltage value close to the target value to a next-stage capacitor Cto be connected to the output side of the amplifier. Such an A/D converter circuitthat can perform speedy convergence to the target value of operational amplification is used at each stage of a pipeline A/D converter.

A semiconductor integrated circuit has a plurality of capacitor cells, and each capacitor cell has an upper electrode and a lower electrode. These electrodes are respectively connected to an upper electrode wiring and a lower electrode. When, for example, the upper electrode is connected to the upper electrode wiring and the electrode wiring is located at a side of the lower electrode of another capacitor cell or a side of the lower electrode wiring connecting these electrodes, a shield wiring is provided between the upper electrode wiring and the adjacently-located lower electrode of the other capacitor cell or between the upper electrode wiring and the adjacently-located lower electrode wiring. Thus, with this shield wiring, the capacitance coupling between each wiring of the capacitor cells and each upper electrode or each lower electrode of the capacitor cells are effectively suppressed.

Semiconductor integrated circuit, D-A converter device, and A-D converter device

In a charge redistribution type A/D converter, an input-side capacitor terminal and a comparator-side capacitor terminal are connected through first and second analog switches to a fixed-voltage supply circuit, and the input-side capacitor terminal is connected through a third analog switch to the outside. Immediately before sampling an analog signal, the first and second analog switches are closed while the third analog switch is opened, according to a RESET signal. Thereby, fixed voltages are supplied to the input-side capacitor terminal and the comparator-side capacitor terminal, respectively, and charge stored in a weighting capacitor unit is initialized to a predetermined value.

The present invention provides a serial/parallel A/D converter which is capable of performing a high-speed and high-accuracy operation even in the case where an analog input voltage Vin greatly varies in a period between a previous sampling period in which the analog input voltage is held and the next sampling period, when converting the analog input voltage Vin input into a digital value. This serial/parallel A/D converter includes a lower-order reference voltage initializing circuit for initializing a lower-order reference voltage to an initialization voltage Vrc . The initialization voltage Vrc is generated as the lower-order reference voltage in an arbitrary period from the start of sampling of the analog input voltage until the start of a comparison operation for the lower-order reference voltage, the value of the lower-order reference voltage is changed from the value of the initialization voltage to a voltage value which is decided on the basis of higher-order code selection signals P C-P C from a higher-order code selecting circuit , and the value of the lower-order reference voltage which is decided on the basis of the higher-order code selection signals P C-P C is compared with the value of the analog input voltage.

A/D conversion method for serial/parallel A/D converter, and serial/parallel A/D converter

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.

Growing community of inventors

Osaka, Japan

Daisuke Nomasaki