AN207 Datasheet, PDF (12/12 Pages) Vishay Siliconix – 12-ns DG611 Switch Family Combines Benefits of CMOS and DMOS Technologies

AN207
Vishay Siliconix
Switch Models
The following static models are useful for analyzing circuit
performance when the switch is fully on or fully off. For the
dynamic parameters such as switching times and charge
injection it is better to refer to the typical characteristic curves
provided in the data sheet.
The on-state model shown in Figure 20 uses typical
parameter values for room temperature. The channel-on
capacitance (C_D(on)) and channel-on leakage (I_D(on)) are
placed on the output side to simulate the worst case possible.
In reality, both parameters are distributed along the channel. If
you would like to refine the model you may want to divide these
lumped parameters into two or three fractions.
Single-Supply Operation
Disk drives and other computer peripherals may only have
+12-V and +5-V power supplies or even just a single +5-V
power supply. It is perfectly possible to operate the DG611 with
the power-supply configurations shown in Figure 21. In case
(c) the logic has to be 12-V CMOS. In (b), the switch
on-resistance will be high and the analog dynamic range will
be reduced to about 0 to 2 V, due to the limited channel
enhancement voltage available. (See Figure 7.)
Conclusion
By integrating fast DMOS FETs with high-speed CMOS
drivers, the DG611 family of monolithic analog switches
improves reliability and reduces part count. These fast analog
switches simultaneously establish new records for high speed,
low charge injection, and low power. These significant
performance achievements bring considerable benefits to
many dynamic switching applications.
References:
Vishay Siliconix, DG611 Data Sheet (FaxBack document
number 70057).
Analog Devices, 1986. Data Acquisition Handbook.
National Semiconductor, 1985. Switched-Capacitor Filter
Handbook.
+5 V +12 V
V_L
V+
DG611
+5 V
V_L
V+
DG612
+12 V
V_L
V+
DG613
GND V–
GND V–
GND V–
a)
b)
c)
FIGURE 21. Unipolar Supply Configurations
www.vishay.com S FaxBack 408-970-5600
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Document Number: 70605
03-Aug-99