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Why is SRAM more expensive then DRAM?

2017-12-28 16:06:58

There’s the technical reason and the real reason.

But first, SRAM uses close to the same FETS and capacitors, so there’s no digital discount over DRAM. Sense amps are cheap compared to the die size cost.

The technical reason has been touched on elsewhere in these answers. An SRAM uses more transistors per bit, so a larger die area is required for the same storage on a die. Since the cost (not price) of a chip is the wafer cost divided by the number of good die, and ( generalization ahead) the cost to produce a silicon wafer is set mostly by the cost of the buildings and equipment (IMPORTANT), larger die cost more than smaller equivalent die.

Now, the REAL reason: Because people will pay more.

Cost and Price are utterly unrelated in commodities like semiconductors. If the supply exceeds the demand for a memory chip, the price comes down until it balances, regardless of the cost to produce it. I managed a team of memory engineers and many years ago held up a reel of 1,000 parts in a team meeting and told my people that these reels were selling for $10,000, but cost us $37,000 to make until they could fix some yield problems. Our cost had no relation to the sale price, if someone else would sell it for less. I told them to imagine tossing the reel into the back seat of a new BMW, driving it to the customer’s front door, and leaving the keys in the car and walking away - that’s how much we were giving away with each one.