Topic Semiconductor Corp.

Winbond Electronics Corporation

Industrial Technology Research Institute

Chu-Chiao Yu

Her-Y Shih

Jean-Ming Lee

Yen-Hui Wang

Shaw-Jia Hor

Jinn-Ann Kuo

A comparator circuit used in an analog-to-digital converter includes an input voltage signal line; a reference voltage signal line; a plurality of comparators connected to said input voltage signal line and said reference voltage signal line; a plurality of amplifiers corresponding separately to each of said plurality of comparators and connected respectively between said input voltage signal lines, said reference voltage signal lines, and their corresponding comparators; and a thermocode channel connected to outputs of said plurality of comparators. A plurality of resistors with resistances in a constant ratio are provided in said reference voltage signal line and each is connected between the inputs of two adjacent amplifiers. A plurality of averaging resistors are provided and each is connected between the drains of the input transistor of two adjacent comparators; wherein said plurality of averaging resistors have the same resistance.

Comparator circuit for analog-to-digital converter

A comparator circuit used in an analog-to-digital converter includes an input voltage signal line; a reference voltage signal line; a plurality of comparators connected to said input voltage signal line and said reference voltage signal line; a plurality of amplifiers corresponding separately to each of said plurality of comparators and connected respectively between said input voltage signal lines, said reference voltage signal lines, and their corresponding comparators; and a thermocode channel connected to outputs of said plurality of comparators. A plurality of resistors with resistances in a constant ratio are provided in said reference voltage signal line and each is connected between the inputs of two adjacent amplifiers. A plurality of averaging capacitors are provided and each is connected between the outputs of two adjacent comparators; wherein said plurality of averaging capacitors may have the same capacitance.

A voltage-controlled oscillator comprising a voltage compensation transistor is disclosed. The voltage compensation transistor is able to provide an equivalent resistance to the bias voltage supplied to the oscillator. When a sudden raise in the voltage of the power supply takes place, the equivalent resistance of the compensation transistor will drop, such that the bias voltage supplied to the oscillator may be pulled down, whereby the oscillation frequency of the ring oscillator may be adjusted.

Voltage-controlled oscillator

The present invention discloses an automatic gain control (AGC) feedback-referenced sigma-delta modulating device provided for processing an analog signal received therein. This device includes an automatic gain controller (AGC) for receiving processing the analog input signal for generating an AGC feedback including a set of positive and negative AGC reference voltages. This device further include a sigma-delta modulator for receiving the analog input signal and the AGC feedback of the set of the positive and negative AGC reference voltages for generating a one binary bit output therefrom. In a preferred embodiment, the automatic gain controller (AGC) includes a peak detector for receiving and detecting a peak input voltage of the analog input signal. The automatic gain controller (AGC) further includes a maximum gain control block for receiving the peak input voltage from the peak value detector for generating a maximum gain controlled peak value Vp. And, the automatic gain controller (AGC) further includes a positive-and-negative AGC reference voltage (Vref,AGC, Vref,AGC) generation block for receiving and applying the maximum gain controlled peak value Vp to generate a positive AGC reference voltage Vref,AGC and a negative AGC reference voltage Vref&minus;_AGC.

Fully integrated architecture for improved sigma-delta modulator with automatic gain controller

An analog modulator employing .DELTA.-.SIGMA. transformation and comprising timings generator, at least a single operational-amplifier (OP-amplifier) filter of Biquadratic transfer function and saturation detection circuit, is provided. This novel approach solves the stability issue by controlling the switching timings of the single operation-amplifier biquadratic filter in the .DELTA.-.SIGMA. modulator. During normal operation, this high-order .DELTA.-.SIGMA. modulator constructed by the single OP-amplifier biquadratic filter functions a third-order or fourth-order modulator. As unstable condition occurs, via the saturation detection circuit and timings generator, the third-order or the fourth-order modulator functionally converts into and performs as a stable .DELTA.-.SIGMA. modulator of second-order. As a stable condition is restored after a recovery time, via controlling the timing signals, the modulator functionally resumes its normal function of third-order or fourth-order operation which has a high resolution.

Stabilization scheme of delta-sigma modulator

The present invention discloses a biquadratic switched-capacitor filter, which merely utilizes one operational amplifier to implement a biquadratic transfer function. The biquadratic switched-capacitor filter further comprises ten switched-capacitor circuits, two feedback capacitors, and two individual switching devices. The switching devices in this switched-capacitor filter can be controlled by six different clock signals. The first and second clock signals are two-phase, complementary but non-overlapping pulse trains with a reference period. The third clock signal is a pulse train with double the reference period and coincident with the first clock signal. The fourth, the fifth, and the sixth clock signals are pulse trains that result from delaying the third, the fourth, and the fifth clock signals by half the reference period. The obtained switched-capacitor filter can be used to simplify some applications, such as sigma-delta modulators.

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Hsin-Chu, Taiwan

Chu-Chiao Yu