Abstract: A high speed frequency generator is disclosed. The frequency generator includes a frequency oscillator producing an output signal of a predetermined frequency, a first frequency divider frequency-dividing the first frequency oscillator's output signal, and a second frequency divider frequency-dividing an input signal by a predetermined factor. A flip-flop receives a signal generated from the second frequency divider and produces an output signal in accordance with an input clock signal. A pulse-width detector detects a width of the output signal of the flip-flop. A comparing part compares an output signal of the pulse-width detector with a reference value to control a counter that counts to a prescribed digital value that corresponds to a desired frequency. A digital-analog converter converts an output digital value from the counter into an analog value.

Abstract: A voltage controlled oscillator (VCO) includes a ring oscillator controlled by an input voltage and having a ring structure, the ring oscillator including a plurality of CMOS inverter amplifiers each having an input and an output, the output of a CMOS inverter amplifier being connected to the input of a next CMOS inverter amplifier, and an inverter for inverting an output value of the ring oscillator.

Abstract: A trigger voltage controllable Schmitt trigger circuit consists of: a trigger-inverting output unit for trigger-inverting input signals in a predetermined margin; a trigger voltage control signal output unit for generating control signals for controlling trigger voltage according to external control signals, the unit including a linear differential amplifier; and first and second trigger voltage control units for changing margins of trigger performed by the trigger-inverting output unit, the units including transistors whose resistance ratios linearly change according to the control signals from the trigger voltage control signal output unit.