7.7 Charge Injection

The TMUX1208-Q1 has a transmission-gate topology. Any mismatch in capacitance between the NMOS and

PMOS transistors results in a charge injected into the drain or source during the falling or rising edge of the gate

signal. The amount of charge injected into the source or drain of the device is known as charge injection, and is

drain (D).

OUTPUT

EN

S1

D

GND

Output

0 V

A0

A1

A2

S2

S8

0.1…F

Figure 7-7. Charge-Injection Measurement Setup

7.8 Off Isolation

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

source pin (Sx) of an off-channel. Figure 7-8 shows the setup used to measure, and the equation to compute off

isolation.

GND

NETW ORK

ANALYZ ER

V

OUT

S

D

50Q

V

SIG

R

L

50Q

S

R

L

50Q

V

S

V

DD

0.1µF

Figure 7-8. Off Isolation Measurement Setup

OUT

S

V

Off Isolation

20 Log

V

§

·

˜

¨

¸

©

¹

(1)

TMUX1208-Q1

SCDS415A – AUGUST 2019 – REVISED JULY 2020

www.ti.com

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