PAM4 transceivers for high-speed communication
The present invention is directed to data communication. More specifically, embodiments of the present invention provide a transceiver that processes an incoming data stream and generates a recovered clock signal based on the incoming data stream. The transceiver includes a voltage gain amplifier that also performs equalization and provides a driving signal to track and hold circuits that hold the incoming data stream, which is stored by shift and holder buffer circuits. Analog to digital conversion is then performed on the buffer data by a plurality of ADC circuits. Various DSP functions are then performed over the converted data. The converted data are then encoded and transmitted in a PAM format. There are other embodiments as well.
1. A transceiver system comprising:
an input terminal for receiving an input data stream, the input data stream being characterized by a first frequency;
an analog front end (AFE) comprising:
a first voltage gain amplifier configured to generate a first driving signal using the input data stream;
a track and hold (T/H) module for tracking and holding the first driving signal at a second frequency to produce a plurality of sample signals, the second frequency being different from the first frequency; and
an analog-to-digital converter (ADC) module for respectively converting the plurality of sample signals to a plurality of digitized sample signals, the ADC module including a plurality of ADC slices respectively corresponding to the plurality of digitized sample signals; and
a digital signal processing (DSP) module configured to calibrate the AFE based on the plurality of digitized sample signals generated from the input data stream, calibrating the AFE including adjusting respective reference voltages of the plurality of ADC slices to compensate for gain mismatches of the digitized sample signals.
2. The system of claim 1 further comprising a delay-lock loop (DLL) for generating timing phases for the ADC module based on the input data stream.
3. The system of claim 1 wherein the second frequency is at about half of the first frequency.
4. The system of claim 1 further comprising a phase lock loop module for recovering a clock signal from the input data stream.
5. The system of claim 1 wherein the DSP module is configured to correct a residual gain error of the AFE that remains after the adjustment of the reference voltages.
6. The system of claim 1 wherein the DSP module comprises a set of parallel feed forward equalizers for performing channel equalization.
7. The system of claim 1 further comprising a regulator coupled to a power source and regulating power supplied to the AFE, the regulator being configured to perform feed-forward injection to attenuate noises associated with the power source.
8. The system of claim 1 wherein the DSP module comprises a baud rate timing recovery module.
9. The system of claim 1 further comprising a clock generation module configured to generate a clock signal based at least on the input data stream and provide the clock signal to the AFE, the DSP module, or both.
10. The system of claim 9 wherein the clock generation module comprises a phase-lock loop (PLL) circuit for performing clock recovery using the input data stream.
11. The device of claim 1 wherein the DSP module further comprises a slicer.
12. A transceiver system comprising:
an input terminal for receiving an input data stream, the input data stream being characterized by a first frequency;
an analog front end comprising:
a first voltage gain amplifier being configured to generate a first driving signal;
a second voltage gain amplifier configured to generate a second driving signal;
a track and hold (T/H) module for holding the first driving signal at a second frequency to produce a first plurality of sample signals and holding the second driving signal at the second frequency to produce a second plurality of sample signals, the second frequency being different from the first frequency; and
an analog-to-digital converter (ADC) module for converting each sample signal of the first and second plurality of sample signals into a respective one of a plurality of digitized sample signals, the ADC module including a plurality of ADC slices respectively corresponding to the plurality of digitized sample signals; and
a digital signal processing (DSP) module configured to calibrate the AFE based on the plurality of digitized sample signals generated from the input data stream, calibrating the AFE including adjusting respective reference voltages of the plurality of ADC slices to compensate for gain mismatches of the digitized sample signals.
13. The transceiver system of claim 12 wherein calibrating the AFE includes the DSP module generating a delay signal to adjust sampling phases used by the T/H module.
14. The transceiver system of claim 12 , wherein the first voltage gain amplifier is characterized by a bandwidth of at least 13 GHz and a gain range of at least 12 dB.
15. The transceiver system of claim 1 , wherein calibrating the AFE includes the DSP module generating a delay signal to adjust sampling phases used by the T/H module.
16. The transceiver system of claim 1 , wherein the first voltage gain amplifier is characterized by a bandwidth of at least 13 GHz and a gain range of at least 12 dB.