In a built-up circuit? I can see it in an IC, provided the switching frequency is sufficiently far out of band. (There's a trick used in high power audio amps, to equalize the supplies: you ground one end of an inductor, and switch the other end from VCC to VEE. Any DC imbalance goes away magically, and the switcher doesn't have to supply the whole load.)
My interest is primarily in making accurate replicas of photocurrents for use in bandaging nonlinearities elsewhere in the system, e.g. Figure
12 ofI've been working for awhile, on and off, to make a noise canceller good to an honest 70 dB from DC to 10 MHz. The analogue accuracy and noise requirements are pretty stringent, and it has to work over about a
1000:1 photocurrent range. The combination makes it very interesting. Even with gussied-up mirrors, it needs three automatic tweaks per photodiode--R_ee' at DC, and AC tweaks of j omega and omega**2.It simulates great, and I have some PDs that by my measurements should be adequate, but we'll see when the boards are done. My beautiful PCB hunchback and opera singer got chucked in the deep end on that one--over
200 parts, all connected to each other. She learned to swim pretty well, and is now doing her first client work. The analogue board will go out to fab later this month.Hopefully Firmware Hunchback and I can get the CPU board done soon, and it'll be a product this year. (I'm like butter spread over too much bread at the moment.)
Cheers
Phil Hobbs