graphics double data rate (memory) (GDDR)
Graphics Double Data Rate (GDDR) are SDRAMs, Synchronous Dynamic RAMs, of graphics cards standardized by the Joint Electron Device Engineering Council( JEDEC). GDDR memories are specially designed for the enormous amounts of data that are generated during graphics processing. Correspondingly powerful graphics cards are used in personalcomputers, desktops and notebooks for high- resolution 3D graphics.
The development of GDDRs goes hand in hand with the development of powerful processors. There are several types of GDDR, which differ in clock speed, bandwidth, data trasfer rate, supply voltage and power management. Uniform for all GDDR versions is the bus width of 32 bits.
Thus, the supply voltage of the first GDDR memories, GDDR1, is 2.5 V and the clock frequencies are between 200 MHz and 500 MHz. With GDDR2, the bit- parallel transmission and thus also the data throughput were doubled. GDDR3 is characterized by a reduced supply voltage of 1.8 V and a clock rate of up to 1.3 GHz. GDDR4 has an even higher clock rate of 1.6 GHz.
The GDDR5 standard has a clock rate between 1.75 GHz and 4 GHz and offers a transfer rate between 3.6 GHz and 8 GHz. The data transfer rate is between 14 GB/s and 32 GB/s. The supply voltage has been reduced to 1.5 V, which helps to save energy. GDDR6 represents the current state of development. The clock rate for the input/output system is between 3.5 GHz and 4.5 GHz, the transfer rate between 14 GHz and 18 GHz, and the data transfer rate between 56 GB/s and 72 GB/s. Furthermore, the supply voltage has been lowered to 1.35 V compared to GDDR5. Unlike all other GDDR versions, the bus system of GDDR6 consists of two 16-bit buses.