System with a clocked interface
View Patent ↗A system with a transmitter for transmitting digital data via an interface to a receiver. The interface has at least one data line and a clock line. A clock generator supplies a clock signal to the clock line. The receiver uses the clock signal received from the clock line for deriving timing information for processing received digital data. The clock signal may have an amplitude that is lower than the power supply voltage VDD, typically less than half of the power supply voltage, and less stringent requirements can be applied to the waveform of the clock signal than traditionally applied to data and clock signals. The clock signals are hereby less power consuming and cause significantly less electromagnetic interference.
1. A system comprising:
a transmitter capable of transmitting digital data,
an interface connected to the transmitter, the interface having at least one data line for receiving and transmitting the digital data from the transmitter, and a clock line for transmitting a clock signal,
a clock circuit for supplying, to the clock line, the clock signal alternating between two signal levels at a predetermined frequency, the two signal levels effecting a low swing to mitigate the generation of electromagnetic interference EMI, thereby providing timing information,
a receiver connected to the interface so as to receive, from the interface, the digital data transmitted on the data line, and so as to receive the clock signal on the clock line,
characterized in that the receiver regenerates an internal clock signal derived from the received clock signal and the receiver uses the clock signal received from the clock line for deriving the timing information for processing the received digital data.
2. A system according to claim 1 , characterized in that the clock circuit for supplying the clock signal to the clock line is included in the transmitter.
3. A system according to claim 2 , characterized in that the receiver receives, as the only clock signal, the clock signal transmitted by the transmitter.
4. A system according to claim 1 , characterized in that the clock circuit for supplying the clock signal to the clock line is a clock signal generator external to the transmitter.
5. A system according to claim 1 , characterized in that the transmitter and the receiver both receive a power supply voltage (VDD) and the two signal levels of the clock signal have a voltage difference that is less than the VDD.
6. A system according to claim 1 , characterized in that
the receiver is also capable of transmitting digital data,
the data line is capable of receiving and transmitting the digital data from the receiver, and the transmitter is capable of receiving the digital data from the interface.
7. A system according to claim 1 , wherein the transmitter and the receiver both receive a power supply voltage (VDD) and the two signal levels of the clock signal have a voltage difference that is less than half of the VDD.
8. A system according to claim 1 , wherein the clock signal is a sine wave signal to mitigate the generation of EMI.
9. A system according to claim 1 , wherein the clock signal is a sine wave signal to mitigate the generation of EMI, the transmitter and the receiver both receive a power supply voltage (VDD), and the two signal levels of the clock signal have a voltage difference that is less than the VDD.
10. A system according to claim 1 , wherein the clock signal is a sine wave signal to mitigate the generation of EMI, the transmitter and the receiver both receive a power supply voltage (VDD), and the two signal levels of the clock signal have a voltage difference that is less than half of the VDD.
11. A system according to claim 1 , wherein the clock line does not transmit digital data.
12. A system according to claim 1 , wherein the internal clock signal is regenerated by reshaping the received clock signal from a sine wave signal into a square wave signal and by amplifying the received clock signal.
13. A system comprising:
a transmitter to transmit digital data;
an interface connected to the transmitter, the interface having at least one data line for receiving and transmitting the digital data from the transmitter, and a clock line for transmitting a clock signal;
a clock circuit to supply a low swing clock signal to the clock line thereby providing timing information, the low swing clock signal alternating between two signal levels at a predetermined frequency, the two signal levels having a voltage difference that is less than one half a power supply voltage (VDD);
a receiver connected to the interface to receive the digital data transmitted on the data line and to receive the low swing clock signal on the clock line as the only clock signal for deriving the timing information for processing the received digital data, the receiver further receives the power supply voltage (VDD) and amplifies and reshapes the received low swing clock signal to thereby regenerate a usable internal clock signal.
14. The system of claim 13 , wherein the low swing clock signal mitigates generation of electromagnetic interference EMI.