DG540/541/542

8

Siliconix

S-53694—Rev. E, 28-May-97

Test Circuits (Cont’d)

X

V

OUT

V

IN

10

W

75

W

V+

V–

+15 V

–15 V

C

C

GND

2.4 V

Figure 6.

All Hostile Crosstalk

Applications

Device Description

The DG540/541/542 family of wideband switches offers

true bidirectional switching of high frequency analog or

digital signals with minimum signal crosstalk, low insertion

loss, and negligible non-linearity distortion and group

delay.

Built on the Siliconix D/CMOS process, these “T” switches

provide excellent off-isolation with a bandwidth of around

500 MHz (350 MHz for DG541). Silicon-gate D/CMOS

processing also yields fast switching speeds.

An

on-chip

regulator

circuit

maintains

TTL

input

compatibility over the whole operating supply voltage

range, easing control logic interfacing.

Circuit layout is facilitated by the interchangeability of

source and drain terminals.

Frequency Response

A single switch on-channel exhibits both resistance

an attenuation effect on the analog signal – which is

frequency dependent (like an RC low-pass filter). The

–3-dB bandwidth of the DG540 is typically 500 MHz (into

50

the switch channel can not be represented by a two stage RC

combination. The on capacitance of the channel is

distributed along the on-resistance, and hence becomes a

more complex multi stage network of R’s and C’s making

for more details.

Off-Isolation and Crosstalk

Off-isolation and crosstalk are affected by the load

resistance

and

parasitic

inter-electrode

capacitances.

gain adjustments down the line. Stray capacitances, even a

fraction of 1 pF, can cause a large crosstalk increase. Good

layout and ground shielding techniques can considerably

improve your ac circuit performance.