transistor array ICs (was, analog multiplier help)

Winfield Hill wrote...
>
> bill.sloman@xxxxxxxx wrote...
>>
>> My impression is that the virtues of dual gate MOSFET mixers have
>> everything to do with the good behaviour of the components at
>> relatively high frequencies.
>>
>> The OP wants good mixing - and explicityl wants to minimise spurious
>> high order product spurs - at frequencies up to 10MHz, A well
>> compensated Gilbert cell multiplier will do much better than a MOSFET
>> for this sort of job. He also wants to use fairly high level signals,
>> which won't work well with a dual -gate MOSFET mixer.
>>
>> The numbers for the MOSFET would have come from "Transistor Circuits
>> and Applications" (Prentice-Hall series in electronic technology) by
>> Laurence G Cowles ISBN: 0139300732.
>>
>> The ISBN is for the second edition from 1974 - I had the first edition,
>> until it got soaked when a pipe froze in Cambridge U.K. some twenty
>> years ago.
>
> Can you still open the pages? Anyway, yes, bipolar transistors in
> a balanced Gilbert cell should do far better than a JFET or MOSFET
> mixer any day, thanks to the BJT's higher transconductance at any
> given operating current. First, the BJT's higher transconductance
> acts to reduce the effects of DC imbalance, and second, the BJT's
> intrinsic DC offsets are much lower than for JFETs or MOSFETs.
> (A caveat must be introduced for high background-noise levels.)
>
> We should point out an excellent high-frequency bipolar Gilbert
> cell IC available from Intersil, the HFA3101. The hfa3101 uses
> 10GHz transistors (10-50mA) that can be used at reduced currents
> like 2 to 5mA, and still yield a superior performance at 10MHz.
>
> http://www.intersil.com/cda/deviceinfo/0,1477,HFA3101,0.html and
> http://www.intersil.com/data/fn/fn3663.pdf DigiKey stocks the
> HFA3101B version at $4.28 each, or $2.48 qty 100. Newark has
> them too, same price singles, but charges $3.65 qty 100.
>
> The HFA3102 is also a useful part, among others in the UHF series.
> http://www.intersil.com/data/fn/fn3635.pdf

Experienced analog engineers will recognize the hfa3101 and 3102
part numbers from the CA3101 and '02 parts introduced by RCA in
the early days of linear ICs. RCA introduced a line of transistor
array ICs that gave analog designers access to powerful matched-
transistor design techniques, routinely used by IC designers, but
otherwise not available to the rest of us. For example, the ca3045,
ca3046 and ca3086 were five-transistor NPN arrays, and the ca3096
was an NPN + PNP array with five "high-voltage" 35V transistors.
NSC chipped in with the LM3046, pardon the pun.

As the years went by, GE, RCA and Intersil became owned by Harris,
who eventually tired of them, and spun them off as Intersil.
http://www.intersil.com/products/deviceresults.asp?i=5500&i=5502

Sadly, most of the old high-voltage (e.g. 15V) arrays have been
discontinued, but a few, like the ca3083, ca3086 and the ca3127
(with 1GHz transistors) have remained, although distributors may
not carry them. The LM3046 is still available, but only in SMD.

In place of the lost "high-voltage" arrays we've gotten a few
newer "low-voltage" parts having the same schematic and pinout,
but made with much faster transistors. The original parts had
through-hole DIP packages, well suited for experimenters, but
the new parts are SMD only.

Here's a little table of the array's NPN transistor properties
to jog our memories, and a comparison to the newer parts.

NPN ca3046
spec ca3086 ca3083 ca3096 ca3127 hfa3127
---- ------ ------ ------ ------ -------
DIP? X X X X soic only
Vceo 15 15 35 15 8 V
IC-max 50 100 50 20 65 mA
beta 100 70 390 85 130
f_T 550 450 335 1100 8000 MHz
C_cb 0.58 - 2.25 0.2 0.6 pF (0.3 on die)
C_sub 2.8 - 3.0 1.3 -

Intersil also offers the hfa3134 and hfa3135, which are NPN
and PNP matched pairs with f_T = 8.5 and 7GHz.


--
Thanks,
- Win
.

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