TMUX7208 datasheet(26/51 Pages) TI2

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7.9 Charge Injection

The TMUX7208 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 denoted

by the symbol QINJ. Figure 7-9 shows the setup used to measure charge injection from source (Sx) to drain (D).

The TMUX7208 and have 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

denoted by the symbol QINJ. Figure 7-9 shows the setup used to measure charge injection from source (Sx) to

drain (D).

VDD

VSS

VDD

VSS

0.1 µF

GND

VEN

VOUT

Output

0 V

3 V

VEN

QINJ = CL ×

VOUT

tr < 20 ns

tf < 20 ns

N.C.

Output

Figure 7-9. Charge-Injection Measurement Setup

7.10 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 7-10 shows the setup used to measure, and the equation used to

calculate off isolation.

TMUX7208, TMUX7209

SCDS418F – JULY 2020 – REVISED JULY 2024

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TMUX7208 Datasheet(PDF) 26 Page - Texas Instruments