US-12626636-B2 - Low voltage differential signaling (LVDS) communication interface connecting liquid crystal controller and liquid crystal driver

Abstract

A circuit includes: a receiving circuit, having a first input terminal for inputting a first signal transmitted via a first capacitive element, and a second input terminal for inputting a second signal transmitted via a second capacitive element and having a potential that changes complementarily to the first signal, and outputting a first logic signal corresponding to a potential of the first signal and a second logic signal corresponding to a potential of the second signal; and a signal supply circuit, supplying a first guarantee signal having a potential corresponding to a value of the first logic signal to the first input terminal as a signal for guaranteeing a potential of the first signal, and supplying a second guarantee signal having a potential that changes complementarily to the first guarantee signal to the second input terminal as a signal for guaranteeing a potential of the second signal.

Inventors

• Kouya SUGIHARA

Assignees

• LAPIS Technology Co., Ltd.

Dates

Publication Date

20260512

Application Date

20240725

Priority Date

20230728

Claims (6)

1. 1 . An alternating current coupling circuit, the circuit comprising: a receiving circuit, having a first input terminal for inputting a first signal transmitted via a first capacitive element, and a second input terminal for inputting a second signal transmitted via a second capacitive element and having a potential that changes complementarily to the first signal, and outputting a first logic signal corresponding to a potential of the first signal and a second logic signal corresponding to a potential of the second signal; and a signal supply circuit, supplying a first guarantee signal having a potential corresponding to a value of the first logic signal to the first input terminal as a signal for guaranteeing a potential of the first signal, supplying a second guarantee signal having a potential that changes complementarily to the first guarantee signal to the second input terminal as a signal for guaranteeing a potential of the second signal, supplying the second guarantee signal of a second potential lower than a first potential to the second input terminal when the first guarantee signal of the first potential is supplied to the first input terminal, and supplying the second guarantee signal of the first potential to the second input terminal when the first guarantee signal of the second potential is supplied to the first input terminal, wherein the signal supply circuit comprises a voltage divider circuit that generates the first potential or the second potential by dividing a voltage applied to a resistor provided between two power sources.
2. 2 . The circuit according to claim 1 , wherein the signal supply circuit comprises: a first switch that is turned on when a value of the first logic signal is a specific potential so as to supply the first guarantee signal of the first potential to the first input terminal; a second switch that is turned on when a value of the second logic signal is a specific potential so as to supply the second guarantee signal of the first potential to the second input terminal; a third switch that is turned on when a value of the second logic signal is a specific potential so as to supply the first guarantee signal of the second potential to the first input terminal; and a fourth switch that is turned on when a value of the first logic signal is a specific potential so as to supply the second guarantee signal of the second potential to the second input terminal.
3. 3 . The circuit according to claim 1 , wherein the receiving circuit includes a differential amplifier circuit receiving the first and second signals.
4. 4 . A communication system, comprising: a first semiconductor device, having a transmitting circuit for transmitting a first signal and a second signal; and a second semiconductor device, having a circuit, the circuit including: a receiving circuit, having a first input terminal for inputting the first signal transmitted via a first capacitive element, and a second input terminal for inputting the second signal transmitted via a second capacitive element and having a potential that changes complementarily to the first signal, and outputting a first logic signal corresponding to a potential of the first signal and a second logic signal corresponding to a potential of the second signal; and a signal supply circuit, supplying a first guarantee signal having a potential corresponding to a value of the first logic signal to the first input terminal as a signal for guaranteeing a potential of the first signal, supplying a second guarantee signal having a potential that changes complementarily to the first guarantee signal to the second input terminal as a signal for guaranteeing a potential of the second signal, supplying the second guarantee signal of a second potential lower than a first potential to the second input terminal when the first guarantee signal of the first potential is supplied to the first input terminal and supplying the second guarantee signal of the first potential to the second input terminal when the first guarantee signal of the second potential is supplied to the first input terminal, wherein the signal supply circuit comprises a voltage divider circuit that generates the first potential or the second potential by dividing a voltage applied to a resistor provided between two power sources, wherein the first signal is supplied to the circuit via the first capacitive element, and the second signal is supplied to the circuit via the second capacitive element.
5. 5 . The communication system according to claim 4 wherein the signal supply circuit comprises: a first switch that is turned on when a value of the first logic signal is a specific potential so as to supply the first guarantee signal of the first potential to the first input terminal; a second switch that is turned on when a value of the second logic signal is a specific potential so as to supply the second guarantee signal of the first potential to the second input terminal; a third switch that is turned on when a value of the second logic signal is a specific potential so as to supply the first guarantee signal of the second potential to the first input terminal; and a fourth switch that is turned on when a value of the first logic signal is a specific potential so as to supply the second guarantee signal of the second potential to the second input terminal.
6. 6 . The communication system according to claim 4 , wherein the receiving circuit includes a differential amplifier circuit receiving the first and second signals.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority under 35 USC 119 from Japanese Patent application No. 2023-123355 filed on Jul. 28, 2023, the disclosure of which is incorporated by reference herein. TECHNICAL FIELD The present disclosure relates to a circuit and a communication system. RELATED ART Patent Document 1 (Japanese translation of PCT international application No. 2001-503182) discloses a receiving circuit for receiving data using a differential signal, which is a balanced signal transmitted by an alternating current (AC) coupling method (see FIG. 4 of Patent Document 1). In the alternating current coupling method, a capacity element that removes a DC signal is placed in the transmission path. For this reason, while the data input to the receiving circuit continues to change, the capacity element is repeatedly charged and discharged, and the potentials of the two signals included in the differential signal, which change in a complementary manner, change to H level or L level. Thus, the receiving circuit may operate normally according to the differential signal. However, when the input data does not change for a certain period of time, the energy stored in the capacity element continues to be discharged, and the potentials of the two signals may become approximately the same level. Thus, the receiving circuit is unable to detect the potential of the differential signal and may malfunction. For this reason, the conventional technology has room for improvement in terms of realizing stable operation of the receiving circuit. The disclosure provides a circuit capable of realizing stable operation. SUMMARY The circuit according to the disclosure is an alternating current coupling circuit, including: a receiving circuit, having a first input terminal for inputting a first signal transmitted via a first capacitive element, and a second input terminal for inputting a second signal transmitted via a second capacitive element and having a potential that changes complementarily to the first signal, and outputting a first logic signal corresponding to a potential of the first signal and a second logic signal corresponding to a potential of the second signal; and a signal supply circuit, supplying a first guarantee signal having a potential corresponding to a value of the first logic signal to the first input terminal as a signal for guaranteeing a potential of the first signal, and supplying a second guarantee signal having a potential that changes complementarily to the first guarantee signal to the second input terminal as a signal for guaranteeing a potential of the second signal. The communication system according to the disclosure includes a first semiconductor device, having a transmitting circuit for transmitting a first signal and a second signal; and a second semiconductor device having the above-mentioned circuit, wherein the first signal is supplied to the circuit via the first capacitive element, and the second signal is supplied to the circuit via the second capacitive element. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing the configuration of the display device according to the embodiment of the disclosure. FIG. 2 is a diagram showing the configuration of the communication system according to the embodiment of the disclosure. FIG. 3 is a diagram showing the configuration of the circuit according to the embodiment of the disclosure. FIG. 4 is a diagram for illustrating the operation of the circuit. FIG. 5 is a timing chart for illustrating the operation of the circuit. FIG. 6 is a timing chart for illustrating the operation of the circuit. FIG. 7 is a diagram showing the communication system according to the comparative example. FIG. 8 is a timing chart for illustrating the operation of the circuit according to the comparative example. DESCRIPTION OF EMBODIMENTS According to the disclosure, a circuit that is capable of achieving stable operation may be provided. The embodiment is described below with reference to the drawings. In addition, the same or similar symbols are used for the same functions and configurations, and descriptions therefor are omitted as appropriate. Embodiment (Display Device) FIG. 1 is a diagram showing the configuration of the display device according to the embodiment of the disclosure. The display device 100 may be interpreted as a display device for a vehicle that is mounted on an automobile or the like. The display device 100 includes a display panel 10, a timing controller 11, driver integrated circuits (IC) 12, and a gate driver 13. The display panel 10 may be interpreted as an image display device such as an LCD display panel or an organic electro luminescence (EL) panel. The timing controller 11 may control the display timing of an image on the display panel 10 by controlling a plurality of driver ICs 12A and the gate driver 13. The timing controller 11 may generate a clock signal and supply the same to the driver ICs 12A. The timi