VREF (voltage reference) power supply circuit of DDR4 (double data rate 4) DIMM (dual in-line memory module)

Abstract

The invention discloses a VREF (voltage reference) power supply circuit of a DDR4 (double data rate 4) DIMM (dual in-line memory module). The VREF power supply circuit comprises a resistance voltage dividing circuit and a voltage follower, the resistance voltage dividing circuit is used for outputting initial reference voltage, and the voltage follower is connected with an output end of the resistance voltage dividing circuit and performs voltage following for the initial reference voltage to obtain VREF. According to the VREF power supply circuit, the voltage follower is added based on the resistance voltage dividing circuit, output impedance of the VREF power supply circuit is reduced by the voltage follower, driving current is increased, and driving capability and anti-interference capability are improved, so that reliability of the VREF power supply circuit of the DDR4 DIMM is improved.

Description

technical field [0001] The invention relates to the technical field of DDR, in particular to a VREF power supply circuit of a DDR4 DIMM. Background technique [0002] DDR (Double Data Rate SDRAM, double data stream SDRAM) can transmit data twice in one clock cycle, and its bus transmission capacity is double that of ordinary SDRAM. DDR4 is the fourth generation of DDR, which has improved compared to previous generations in terms of power consumption and transmission speed. DDR4 DIMM (Dual-Inline-Memory-Modules, dual-inline memory module) is a DIMM composed of multiple DDR4 memory particles, also known as a memory stick. [0003] DDR4 uses the SSTL level standard, please refer to figure 1 , figure 1 It is the schematic diagram of the input and output mode of DDR4, and its power supply can be divided into three categories: 1. Main power supply VDD and VDDQ; 2. VTT for terminal matching; 3. Reference power supply VREF. Among them, VREF is used as a reference voltage for jud...

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Problems solved by technology

However, with the increase of DDR4 clock speed, the bus frequency often works at 1.2GHz, and the high-frequency noise generated by various data lines and clock lines will also interfere with the VREF obtained by the voltage divider circuit, reducing the reliability of the resistor divider circuit. sex

In addition, in DDR4DIMM, generally 4 or 8 DDR4 particles constitute a 64-bit bus, which means that VREF must provide reference voltages for dozens of address and command lines in 4 or 8 chips at the same time, and the current consumption increases , so that VREF≠VDDQ / 2 of the divided voltage output further reduces the reliability

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