What is the simplest analog divider circuit?

[Ahmed Alaa]

Hi all,

What is the simplest circuit to divide two signals without using a gilbert cell?

thnx,

 

[Prototyp_V1.0]

What kind of signals?

 

[Ahmed Alaa]

Analog voltage/current signals...

 

[keith1200rs]

Analog voltage/current signals...

Do you mean an arithmetic divider? E.g. Vout = Vin1/Vin2?

What frequency?

Keith

 

[Ahmed Alaa]

Yes, an arithmetic divider that operates ideally at any frequency.

 

[keith1200rs]

Yes, an arithmetic divider that operates ideally at any frequency.

You will have to give more sensible information if you want help. DC-1THz isn't possible. You can make a logamp with a matched transistor pair and an opamp. How many quadrants do you need it to operate over?

Keith

 

[FvM]

an arithmetic divider that operates ideally at any frequency

Keep on dreaming.

From the existing analog multiplier/divider variants, only "gilbert cell" (gm multiplier) is wideband. Log/antilog offers higher dynamic range but
is restricted to MHz bandwidth at best, hall sensor multipliers (rather unusual) possibly achieve a similar speed, PWM multipliers
have only kHz bandwidth.

 

[Ahmed Alaa]

Actually I am tolerant about the operating frequencies, I just want to know what circuits could divide. You're just stating multipliers but I don't know how to wire them as dividers..are all dividers originally multipliers wired as dividers?

 

[FvM]

all dividers originally multipliers wired as dividers?

It's at least the case with gm-multipliers. Some can work as divider by connecting an internal amplifier respectively, others need an additional OP. The manufacturer datasheets tell in detail. A log/antilog circuit computes the quotient directly:

q = a/b = exp(log(a) - log(b))

 

[Ahmed Alaa]

What about an inverting amplifier with one of the two resistors replaced by a voltage controlled resistor?

 

[FvM]

What about an inverting amplifier with one of the two resistors replaced by a voltage controlled resistor?

Basically another good suggestion. You have to care however for a linear dependance of either resistance or conductance
on the input voltage, which involves a control loop and two matched variable resistors in practice. It can work with FETs or for
rather low speeds with LDRs.

 

[Ahmed Alaa]

thnx FvM ! I managed to simulate the divider using my multiplier wired as a divider.