8.2.1.2 Detailed Design Procedure

The application shown in Figure 8-1 demonstrates how to use a single control input and toggle between gain

settings of -1 and +1. If switching between inverting and unity gain is not required, the TMUX1219-Q1 can

be utilized in the feedback path to select different feedback resistors and provide scalable gain settings for

configurable signal conditioning.

The TMUX1219-Q1 can be operated without any external components except for the supply decoupling

capacitors. The select pin is recommended to have a weak pull-down or pull-up resistor to ensure the input is in

a known state. All inputs to the switch must fall within the recommend operating conditions of the TMUX1219-Q1

including signal range and continuous current. For this design with a supply of 2.75 V the signal range can be 0

V to 2.75 V and the max continuous current can be 30 mA.

8.2.1.3 Application Curve

Source or Drain Voltage (V)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

20

40

60

80

VDD = 1.08V

VDD = 1.62 V

VDD = 3 V

VDD = 4.5 V

D001

TA = 25°C

Figure 8-2. On-Resistance vs Source or Drain Voltage

8.2.2 Input Control for Power Amplifier

Another application of the TMUX1219-Q1 is for input control of a power amplifier. Utilizing a switch allows a

system to control when the DAC is connected to the power amplifier, and can stop biasing the power amplifier by

switching the gate to GND. Figure 8-3 shows the TMUX1219-Q1 configured for control of the power amplifier.

RF Output

TMUX1219

SEL

1.8 V

DAC

0 V

5 V

RF Input

Figure 8-3. Input Control of Power Amplifier

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TMUX1219-Q1

SCDS480 – SEPTEMBER 2024

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