阅读说明：本技术 具有pvt补偿的信号丢失检测器 (Loss of signal detector with PVT compensation ) 是由 刘晓群 赛马克·德尔沙特伯 艾哈迈德·亚兹迪 于 2019-07-26 设计创作，主要内容包括：一种电子电路,其包括均衡器电路、整流器电路、复本电路和比较器电路,所述均衡器电路用于输入差分信号；所述整流器电路用于接收所述差分信号并输出第一电流和第二电流；所述复本电路用于接收差分阈值信号并输出第三电流和第四电流,以补偿所述第一和第二电流中的PVT变化；所述比较器电路被配置成比较基于所述第一、第二、第三和第四电流产生的差分电压,以确定所述电子电路的信号丢失事件。(An electronic circuit comprising an equalizer circuit, a rectifier circuit, a replica circuit, and a comparator circuit, the equalizer circuit for inputting a differential signal; the rectifier circuit is used for receiving the differential signal and outputting a first current and a second current; the replica circuit is used for receiving a differential threshold signal and outputting a third current and a fourth current so as to compensate PVT changes in the first current and the second current; the comparator circuit is configured to compare differential voltages generated based on the first, second, third, and fourth currents to determine a loss of signal event of the electronic circuit.)

1. An electronic circuit, comprising:

an equalizer circuit for inputting a differential signal and outputting a differential equalized signal;

a rectifier circuit for receiving the differential equalization signal and outputting a first current and a second current;

a replica circuit for receiving a differential threshold signal and outputting a third current and a fourth current to compensate for PVT variations in the first and second currents; and

a comparator circuit configured to compare differential voltages generated based on the first, second, third, and fourth currents to determine a loss of signal event of the electronic circuit.

2. The electronic circuit of claim 1, wherein the first current from the rectifier circuit is added to the third current from the replica circuit and flows through a first output resistor to determine a signal to be input to a non-inverting input of the comparator.

3. The electronic circuit of claim 1, wherein the second current from the rectifier circuit is added to the fourth current from the replica circuit and flows through a second output resistor to determine a signal to be input to an inverting input of the comparator.

4. The electronic circuit of claim 1, wherein the differential equalization signal comprises a first equalization voltage, a second equalization voltage, and an equalization common voltage.

5. The electronic circuit of claim 4, wherein the first equalization voltage controls a first transistor of the rectifier circuit and the second equalization voltage controls a second transistor of the rectifier circuit.

6. The electronic circuit of claim 4, wherein the equalized common voltage jointly controls a third transistor and a fourth transistor of the rectifier circuit.

7. The electronic circuit of claim 1, wherein the electronic circuit is fabricated on a chip having a bandgap voltage, and wherein the output threshold of the electronic circuit is based on a multiple of the bandgap voltage.

8. A method of operating an electronic circuit, comprising:

inputting a differential signal and outputting a first equalizing voltage, a second equalizing voltage and an equalizing common voltage;

using the first equalized voltage, the second equalized voltage, and the equalized common voltage in a rectifier circuit to produce first and second currents each having PVT variations;

inputting a threshold signal to a replica circuit to generate third and fourth currents to cancel the PVT variations of the first and second currents;

determining a first voltage based on the first and third currents;

determining a second voltage based on the third current and a fourth current; and

comparing the first voltage and the second voltage to determine a loss of signal event in the electronic circuit.

9. The method of claim 8, wherein the first equalizing voltage controls a first transistor of the rectifier circuit, the second equalizing voltage controls a second transistor of the rectifier circuit, and the equalizing common voltage controls third and fourth transistors of the rectifier circuit.

10. The method of claim 8, wherein the threshold signal comprises a differential signal and a common reference signal.

Technical Field

Embodiments disclosed herein relate generally to detection of signal loss in high speed circuits.

Background

In a Universal Serial Bus (USB) or Display Port (DP) high-speed redriver (re-driver) system, a loss of signal (LoS) detector is located at the input of the high-speed redriver to detect the presence of a high-speed signal. When the input signal level is below the LoS detector threshold (e.g., a differential peak-to-peak value of 40 mV), the LoS detector triggers a loss of signal event and the system disables the high-speed redriver to save power consumption or avoid amplifying noise or corrupted signals. Conventional designs of LoS detectors have been extremely low in accuracy and have become a design bottleneck for high-speed redriver systems when high-speed signals are attenuated by long Universal Serial Bus (USB) or Display Port (DP) cables. According to embodiments described herein, the threshold accuracy of a LoS detector is improved by using replica circuitry of the rectifier to compensate for process, supply voltage, and temperature (PVT) variations of the rectifier.

Disclosure of Invention

A brief summary of various embodiments is presented below. Some simplifications and omissions may be made in the following summary, which is intended to highlight and introduce some aspects of the various exemplary embodiments, but not to limit the scope of the invention. Detailed descriptions of embodiments sufficient to allow those of ordinary skill in the art to make and use the inventive concepts will be presented in subsequent sections.

Drawings

Other objects and features of the present invention will become more fully apparent from the following detailed description and appended claims when taken in conjunction with the accompanying drawings. While several embodiments are illustrated and described, like reference numerals represent like parts throughout the several views of the drawings, wherein:

fig. 1 illustrates a loss of signal detector according to embodiments described herein; and

fig. 2 shows the topology of the loss of signal detector according to fig. 1.

Embodiments include an electronic circuit comprising an equalizer circuit to input a differential signal and output a differential equalized signal, a rectifier circuit to receive the differential equalized signal and output a first current and a second current, a replica circuit to receive a differential threshold signal and output a third current and a fourth current to compensate for PVT variations in the first and second currents, and a comparator circuit configured to compare differential voltages generated based on the first, second, third, and fourth currents to determine a loss of signal event for the electronic circuit.

The first current from the rectifier circuit may be added to the third current from the replica circuit and flows through a first output resistor to determine a signal to be input to a non-inverting input of the comparator.

The second current from the rectifier circuit may be added to the fourth current from the replica circuit and flows through a second output resistor to determine a signal to be input to an inverting input of the comparator.

The differential equalization signal may include a first equalization voltage, a second equalization voltage, and an equalization common voltage.

The first equalization voltage may control a first transistor of the rectifier circuit and the second equalization voltage controls a second transistor of the rectifier circuit. The equalized common voltage may jointly control a third transistor and a fourth transistor of the rectifier circuit.

The electronic circuit may be fabricated on a chip having a bandgap voltage, and wherein the output threshold of the electronic circuit is based on a multiple of the bandgap voltage.