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Relation between slew rate and gain-bandwidth product?

Hi~

I've posted the following text to the sci.electronics.design group. But it seems so fundamental to post to the group, so I post it again here.

------------------------------------------------------------------------------------------------------- Hi~

Can someone tell me the relation between slew rate and gain-bandwidth product? Though the relation is not direct, I've been thought that the more the slew rate is the higher the gain-bandwidth product is. But I found that the MP103 from Apex(now Cirrus) has 167V/usec slew rate and 250kHz gain- bandwidth product and the MP111 has 130 V/usec and 6MHz gain-bandwidth product. Is there any relationship between these two properties? I've been thought that the high gain-bandwidth product means high speed, so it also means high slew rate. It will be helpful to tell me any kinds of materials on this.

Thanks.

Reply to
Gundal21
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Slew rate related to the actual voltage and maximum frequency at that voltage and only losely to the GBWP. Given a sine wave of frequency wt, the voltage, V = Vp*sinwt. The slew rate is the first derivitive of the voltage: dV/dt = Vp*w*coswt. w is omega = 2*pi*f, and the maximum value of the cosine = 1.

Therefore the slew rate, p = dV/dt = Vp*2*pi*f

Example: if the peak voltage, Vp = 10 volts, the frequency = 1 MHz, p =

2*10*pi*10^6 = 62.8*10^6 volts per second or 62.8 volts per microsecond.

The slew rate of amplifiers and other circuits is determinded by the current available to charge and discharge the capacitances in the circuit. dv = (1/C)int *i *dt. In most amplifiers, there is a dominant capacitace usually used for compensation that the available current must charge and discharge. That usually defines the slews rate as well as the GBWP. But the relation is not simple because the available voltage must be taken into account.

Reply to
Bob Eld

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If it helps - Bw = .35 x rise time

Reply to
bg

Only if you reciprocate something.

Reply to
JeffM

good catch, thx make that bw = .35 x 1/t bg

Reply to
bg

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