MMIC filter

Agreed! Only an octave wide though—I thought you were bored with sine waves?

Cheers

Phil Hobbs

Reminds me of the ATEK950P6. I find it hard to believe that they get such good results with on-chip inductors, but maybe they can afford a better process than I was used to.

More like 3:1 actually. See fig 5 of the data sheet.

I really want an IC sharp octave filter in the 25-50 MHz sort of range, with a comparator, as a DDS output gadget. I'm using discrete LCs for the filter and an LVDS receiver as the comparator. But the ADI part costs about 100x what my parts cost.

TI or somebody is doing BAW as monolithic layers inside an IC, but that's still nose-bleed GHz frequencies.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

MEMS could make filters in the below-100 MHz range.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

TI are making some very nice BAW clock oscillators which have excellent stability and phase noise. They are very reasonably priced, especially the low frequency ones with single-ended outputs.

John

Good on-chip oscillators would be cool, on uPs and FPGAs.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

I have an electric oven that seems to use the on-chip oscillatior. The clock gains a few minutes a day. Thay could have omitted the clock and no one would miss it.

It's a silicon oscillator factory calibrated to 1%, but drifts a few per cent over temperature.

Some silicon oscillators are specified for 2:1 frequency range.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

But some more so that others. I had cheap Casio watch that I bought in the 1980's and it went through three lithium batteries until I managed to leave it in the washing machine a couple of years ago, which wrecked it.

It's equally cheap Casio replacement - WR100M - is appreciably less temperature dependent than it's predecessor. It loses or gains perhaps a couple of seconds a month. I check it against my computer clock from time to time, and it is more than a few seconds out I reset it, but only once or twice a year.

If you spend enough money you can put a rubidium clock on a printed circuit board but it is a lot bulkier than a single chip.

Probably all watches now have an off-chip quartz tuning-fork resonator, usually 2^15 Hz. MEMS resonators are getting pretty good lately, and the resonator and the oscillator circuit can be on the same silicon chip, so I expect MEMS watches soon.

Bulova once made a watch that used a low frequency tuning fork resonator that directly operated a tiny ratchet.

Given that everybody carries a phone now, why have a watch?

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

how else are you going to show off how much money you have?

My phone is a flashlight, an RPN calculator, a clock/stopwatch, a calendar, a really good camera, maps, a USB memory stick, and a phone.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

The thing to watch is Bragg mirror resonators operating in the GHz, which are very stable and immune to acceleration. I forget the name of the maker.

My phone is in my pants pocket, often awkward to get out to use, especially when driving. Glancing at a wristwatch is far easier. Nor does a simple wristwatch get confused or hacked.

Joe

We had a problem with Apple phones here at CERN. People working with helium found that their phone soon broke down. It turned out that helium leaking into the (MEMS based?) resonator damped it enough to kill the clock oscillator.

Jeroen Belleman

TI. They operate at 2.5GHz and divide down to the specified output frequency.

It is nice but AD wants over 700 bucks for it, per Digikey. For just one of them. And no stock.

I think I stay with varicap diodes, PIN diodes and inductors for a while, at least until prices come down and stock qties go up :-)

Digikey always wants big bucks for things that are not in stock. That's a strange business model.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Not really. You have to pay interest on the capital value of every part you hold in stock, so you only stock stuff you think will sell steadily.

Advertising stuff that you don't stock also costs money, and you have to recover that from each one that gets ordered and sold - and if that was going to happen often you'd carry a stock.

Or until you realise that you need a more stable oscillation frequency.

That may take a while.

Oh.

I take lots of pictures: whiteboards, sketches, scope screens, parts, outdoor stuff. My phone is a nice thin camera. My vision is mediocre, and the phone makes a great magnifier.

The flashlight function is very handy too.

All my old HP calculators are dying, so the RPN on the phone is great.

I rarely use the phone as a phone, and never text.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics