Fun with CMOS - part 3 - Emma ReezaFratZitz (with Boneyard mod)

They differ in just about every way possible. The simple gain calculation is not accurate and the accurate gain calculation is not simple.

Opamps have an open-loop gain of 100,000 or more. In linear mode, CMOS gates have an open-loop gain somewhere between 10 and 100. It varies with power supply voltage and from part-to-part. This sets an upper limit on gain and it complicates the gain calculation because we have to account for the low open-loop gain.

CMOS gates can only be configured as inverting amplifiers be cause they do not have a + input.

Opamps have a very low output impedance, under 100Ω. In linear mode, CMOS gates have an output impedance of several KΩ or more. Because of that, loading reduces the open-loop gain. The feedback loop will load the gate unless we use very large resistor values. Large resistor values will interact with stray capacitance, limiting bandwidth. The next functional block in the circuit can also load the gate.

The two best options are LTSpice and breadboard testing. I do both. Even with all that, I expect a certain amount of variability from part-to-part.
 
Last edited:
My personal policy is that the merchandise should cost more than shipping. I choose the quantities accordingly.

My friendly neighborhood Electronics Store has 4000-series CMOS. I already bought all of the "good" CD 4049s & CD4069s. They have CD4007, but I already stocked up on a Mouser order.
 
Chuck D. Bones said:
My personal policy is that the merchandise should cost more than shipping. I choose the quantities accordingly.

My friendly neighborhood Electronics Store has 4000-series CMOS. I already bought all of the "good" CD 4049s & CD4069s. They have CD4007, but I already stocked up on a Mouser order.
Click to expand...
You still have a friendly neighborhood electronics store lol!?
 
Chuck D. Bones said:
My personal policy is that the merchandise should cost more than shipping. I choose the quantities accordingly.

My friendly neighborhood Electronics Store has 4000-series CMOS. I already bought all of the "good" CD 4049s & CD4069s. They have CD4007, but I already stocked up on a Mouser order.
Click to expand...
Same, I don't know what I might want to build in the future, might as well build up a bit of a stash and save on later shipping.
 
Pre-retirement order - Subtotal = $756.891, shipping and handling = $205.36, or 27.1%. They had a UPS option this time which was $80 less than DHL. I don't remember seeing that the last time I ordered. Ordered late on 5-4, got an email saying it cleared customs and will be delivered on 5/7. Wow. Way faster than the last order. Tayda has a warehouse in Colorado, but it said 'cleared customs'. Seems too fast to be shipped from Thailand.
 
I remember a time when Tayda discounted the shipping for large $ orders. Did Tayda separate out the tariff costs? Or maybe they're rolled up in the shipping cost?
 
Chuck D. Bones said:
I remember a time when Tayda discounted the shipping for large $ orders. Did Tayda separate out the tariff costs? Or maybe they're rolled up in the shipping cost?
Click to expand...
Rolled up into 1 fee. I like the response time, 3 days from Thailand to CT. But 27% is more than I like.
 
You must log in or register to reply here.
Back
Top