It's very doubtful anyone would come out with something like that in this day and age. There is no market for it.
Personally I am always a bit hesitant to use stuff like this in client's designs. I have seen too many of those panacea chips bid an early farewell because the market shriveled up or a key account was lost. Since those things don't have a dynamic range to write home about anyhow, no chance to roll your own? Maybe use a dual-gate FET? This puppy can be had for under 15c (in qties):
Yeah, understood. Presumably the only reason the SA607 came out in a 3.3V version was due to the extra goodies on it making it a decent design in for enough more years that voltages had shifted.
I suspect they're probably still making SA602s and SA607s in the millions per year, actually, and they're unlikely to disappear any time soon.
There is a chance if the technical risk can be minimized. For me personally, I'm inexperienced/unknowledgable enough that doing all of an oscillator, mixer, and possibly amplifier with performance as good as what you get off-the-shelf in an IC and -- just as importantly here -- as low power (the SA607 is 3.5mA!) in, say, a month is definitely a little risky. (Board space is also an issue too -- the SA607 is available in a TSOP-20, and you can't get
*too* much in that space when it's all discrete trasnsitors and 0603 or 0402 bias components.) Of course there is next week when no one expects anything to get done and hence I could play some... if we go that route and it all fails we can just call you up and pay you to come fix it, right? :-)
Ah, the BF998... yes, certainly quite popular... I'll go take a look...
For a crystal oscillator... I'm tempted to just use a single-gate inverter (not Schmitt trigger, I've learned that lesson) biased into its linear region. Would you think that's resaonable vs. using and biasing a transistor instead? (Price is not at all a driving factor here... think space and power consumption still.)
I like 74HCU04 (U = unbuffered) for oscillators. I usually put some resistance between the gate output and the crystal to avoid over-driving. You'll get a nice sine-wave at the other side of the crystal, which you can couple to g2 on your dual gate MOSFET.
I think you could do a discrete oscillator in about the same space as with a logic gate. Using a JFET would minimise biasing components.
You could use teh SA607 and just take the mixer/oscillator section since it's nicely split off from the remainder of the chip.
Probably. But it's a bit pricey by now for my taste. Ok for low qty designs though because your engineering Dollars need to be amortized.
Yes, but not next week ;-)
I won't get any play time. Two clients have deadlines to meet so I had to tell my wife that there won't be much of a vacation. The big Digikey and Mouser orders will arrive on Dec-26. In Germany where we lived before that would have been a holiday, Fedex wouldn't even have come.
That is one popular method, especially if you can use some of the other inverters elsewhere. But mind the max dissipation of the crystal.
Yes, that's what I'm doing at the moment. It works OK, but I was hoping to find something a little better. Besides the unused portions, I also see a fair amount (perhaps +/-6dB) of gain difference in the IF amps between different ICs. Since the thing was designed for FM detection, this isn't completely unreasonable (the data sheet only lists typical gain, not providing limits), but I'd like something a little tighter if possible (+/-2dB would be a lot nicer...).
On the upside, I haven't seen anything that can do what the SA607 does for the same current consumption, though.
I was thinking single-gate inverter... just a little more compact than rolling my own.
I like other distributors as well and sometimes they have better prices. However, most seem unable to set up an efficient search engine and as they say, time is money when a client is paying the hours.