AS

“АLFA RPAR”

Joint Stock Company ALFA

Riga, Latvia www.alfarzpp.lv; alfa@alfarzpp.lv

2019 v.1

3

AS3363

Application information

IC consists of 3 VCA blocks, which are controlled by voltage with maximum output current till

±100 µA each.

Outputs of

VCA can be connected together

, allowing current summing from different VCA’s. Maximum output voltage on each VCA

can’t exceed ±200 mV. If higher voltage is needed - IU converter must be used.

VCA1 and VCA2 each has one input signal. VCA3 has two non-inverting input signals IN3A and IN3B. Maximum voltage

on these inputs can’t exceed ±40mV , thus attenuator must be used with 1k resistor connected to GND.

Each VCA has two control inputs CVMix and Vcntrli, with input voltage ranging from -2V to +2V.

Control voltages

CVMix1 and CVMix2 allows to change amplification on the VCA output from maximum positive to maximum negative

“through silence”.

For example:

If CVMix = +2V -> VCA output = maximum non-inverted input signal,

If CVMix = -2V

-> VCA output = maximum inverted input signal,

If CVMix = 0V

-> VCA output = positive and negative signal are 100% subtracted (silence).

CVMIix3 of VCA3 controls mixing of input signals IN3A and IN3B:

If CVMix3 = +2V -> VCA output = maximum amplification from input IN3A,

If CVMix3 = -2V

-> VCA output = maximum amplification from input IN3B,

If CVMix3 = 0V

-> VCA output = balance from IN3A and IN3B -> 50/50.

Vcntrl1,2,3

– controls output currents of VCA1,2,3 to attenuation -100dB:

if Vcntrlx = +2V -> VCA provides maximum current to output,

if Vcntlrx = 0V

-> VCA provides approximately 50% of maximum current,

if Vcntlrx = -2V

-

> turns “OFF” output current.

For VCA1 and VCA2 mathematical equation is:

Ioutx ~ (Inx * CVMix - Inx (1-CVMix) ) * Vcntlx)

For VCA3 mathematical equation is:

Iout3 ~ (In3A *CVMix3 - In3B *(1- CVMix3) ) * Vcntl3)

Other possible

method of controlling VCA’s:

CVMix VCA1 and VCA2 are used only as activation of function "direct" or "inversed" signal transfer, and Vcntrl for

independent linear control of chosen direct or inversed signals.

CVMix3 of VCA3 can be to used only for chose of transfer from In3A or from In3B, and Vcntrl for independent linear control

of amplification of chosen input.

In such application amplification can be controlled independently and inputs CVMix and Vcntrl "change" one another.