8.7 Charge Injection

Charge injection is a measure of the glitch impulse transferred from the digital input to the analog output during

switching, and is denoted by the symbol QINJ. Figure 8-7 shows the setup used to measure charge injection from

the source to drain.

VOUT

Output

VS

0 V

3 V

VEN

QINJ = CL ×

VOUT

SW

S1

S2

D

SW

S8

GND

GND

SW

GND

Decoder

A0

A1

A2

GND

GND

VS

GND

EN

CL

VEN

Output

tr < 20 ns

tf < 20 ns

VDD

VSS

VDD

VSS

GND

0.1 µF

GND

0.1 µF

Figure 8-7. Charge-Injection Measurement Setup

8.8 Off Isolation

Off isolation is defined as the ratio of the signal at the drain pin (Dx) of the device when a signal is applied to the

source pin (Sx) of an off-channel. The characteristic impedance for the measurement (ZO) is 50 Ω. Figure 8-8

shows the setup used to measure off isolation.

Ax, EN

GND

VAX

VEN

SX

D/ DX

Other

Sx/ Dx

Pins

VS

VOUT

RS

SW

N.C.

SW

N.C.

50Ÿ

Network Analyzer

SW

1BB +OKH=PEKJ = 20 × .KC

8176

85

VDD

VSS

VDD

VSS

GND

0.1 µF

GND

0.1 µF

Figure 8-8. Off Isolation Measurement Setup

www.ti.com

TMUX8108, TMUX8109

SCDS435B – SEPTEMBER 2021 – REVISED AUGUST 2023

Copyright © 2023 Texas Instruments Incorporated

Submit Document Feedback

21

Product Folder Links: TMUX8108 TMUX8109