Semiconductor Technology Academic Research Center

Gunma University

Hao San

Haruo Kobayashi

Hiroyuki Hagiwara

Atsushi Wada

Hiroki Wada

Atsushi Motozawa

Akira Hayakawa

Toshiro Tsukada

Yoshitaka Jingu

Kazuyuki Kobayashi

To provide a complex bandpass &#x394;&#x3a3;AD modulator capable of suppressing the influence of an image component caused by a mismatch between I- and Q-channels on a signal component with low power consumption. A complex bandpass &#x394;&#x3a3;AD modulatoris configured by a subtraction unit, a complex bandpass filter, an addition unit, a noise extraction circuit unit, an ADC unit, and a DAC unit. The noise extraction circuit unitextracts a quantized noise signal of the ADC unitbased on an input signal of the ADC unitand an output signal of the DAC unit, delays the extracted quantized noise signal by one sample time, phase-rotates the delayed signal by a predetermined angle, and feeds back the rotated signal to the input side of the ADC unit. Thus, a complex bandpass &#x394;&#x3a3;AD modulator capable of suppressing the influence of the image component caused by a mismatch between I- and Q-channels on the signal component with low power consumption is provided.

Complex bandpass &#x394;&#x3a3;AD modulator and digital radio receiver

A high-precision &#x394;&#x3a3; modulator reduces nonlinear noise due to the use of a multibit DAC and has little hardware and power consumption. A digital signal is DA converted and fed back to a subtraction circuit supplied with an analog signal. The DAC used in this feedback circuit uses a DAC (DWADAC) that includes a weighted pointer so that input digital signals are supplied in order to a plurality of segment elements that construct the DAC. In this DWADAC, the construction and number of the pointer is set based on the type and order of the filter disposed before the ADC.

High-precision multi-band pass &#x394;&#x3a3; modulator

In a first-order complex band-pass filter, multiplexers are alternately switched over between time intervals of phases A and B, where the multiplexers includes two multiplexers provided at input and output stages, and a multiplexer provided in a feedback circuit of each of first-order filters and being switching over whether to invert a sign of a feedback signal. Then in a circuit part sandwiched between the multiplexers, a processing performed by an I circuit part and a processing performed by a Q circuit part are alternately switched over so that a sign of a signal inputted to an adder is inverted.

Complex band-pass filter for use in digital radio receiver and complex band-pass &#x394;-&#x3a3; AD modulator using the same

A complex band-pass &#x394;&#x3a3; AD modulator is provided with a subtracter device, a complex band-pass filter, first and second AD converters, and first and second DA converters. The first and second DA converters and first and second logic circuits are sandwiched by first and second multiplexers. At a first timing of a clock signal, the first multiplexer inputs and outputs the first and second digital signals as they are, and at a second timing thereof, the first multiplexer inputs the first and second digital signals, and outputs the first digital signal as a second digital signal and outputs the second digital signal as a first digital signal. The second multiplexer inputs and outputs first and second analog signals similarly. The first and second logic circuits substantially noise-shapes non-linearities of the first and second DA converters by realizing complex digital and analog filters, using high-pass and low-pass element rotation methods.

Complex band-pass &#x394;&#x3a3; AD modulator for use in AD converter circuit

A DA converter circuit is provided for use in a &#x394;&#x3a3; AD modulator. The DA converter circuit includes a DA converter of segment switched capacitor type. The DA converter includes an operational amplifier, capacitors as connected in parallel to each other to supply electric charges to the operational amplifier, an electrically charging switch for switching of electrically charging electric charges onto the respective capacitors or not, and an electrically discharging switch for switching or not electrically discharging electric charges from the respective capacitors or not. A switch device performs either one of the electrically charging, the electrically discharging, grounding, and polarity inversion onto the respective capacitors. A controller controls the electrically charging switch, the electrically discharging switch and the switch device to execute a process of second-order DWA algorithm for performing a second-order noise shaping of a non-linearity of the DA converter circuit.

Growing community of inventors

Gunma, Japan

Hao San