Hitachi, Ltd.

Hitachi Communication Systems, Inc.

Nobuaki Kanazawa

Masao Mizukami

Kunihiro Ito

Signal receiving circuit and digital signal processing system

A differential type MOS transmission circuit includes a signal driving circuit and a signal receiving circuit to realize high speed transmission for a short distance transmission between different LSIs, etc. A pair of transmission lines between the signal driving circuit and the signal receiving circuit are driven by a pair of drivers in the signal driving circuit so as to take either one of three states, i.e. one state where both of the lines are in a precharged states and two states where either one of the lines is in a discharged state. A signal driving circuit includes signal generating circuits generating variations in control signals varying pulse-like in response to rise and fall of an input signal to thereby obtain the discharge state. The signal receiving circuit generates an output signal depending on the state of the transmission lines and is constructed of a Schmitt trigger circuit with a hysteresis characteristic, for which an input threshold voltage for output logical values has a level smaller than a potential difference between the precharged level and the discharged level.

Differential type MOS transmission circuit

A signal transmission system provides stable, fast, long-range transmission. During transmission, a short-width pulse is synchronized with rising and falling edges of a transmission pulse signal. A ternary output signal in a differential shape is produced on the basis of the pulse, and an output signal is transmitted through series resistors via a pair of transmitting wirings. During reception, a reception terminal is provided with terminal resistors corresponding to a characteristic impedance of the transmitting wirings. A signal having passed through one of the transmitting wirings is detected with reference to a signal having passed through the other transmitting wiring. A signal having passed through the other transmitting wiring is detected with reference to the signal having passed through the one transmitting wiring. Additionally, the original pulse signal is restored and reproduced on the basis of the detected signals. The signals to be transmitted through the paired transmitting wirings are bipolar pulses or differential pulses which are generated only at the rising and falling times of the pulse signal to be transmitted. The pulses are given a complementary transmission waveform having a small amplitude divided by the series resistors at the transmission side and the terminal resistors at the reception side. In consideration of the above, and since the signals containing no-DC component can be transmitted, the charging and discharging phenomena of the inter-line capacities and the DC shift can be eliminated to accomplish long-range transmissions at a high speed.

Growing community of inventors

Akishima, Japan

Nobuaki Kanazawa