TA31275FN/ TA31275FNG

03-01-23

10

Cautions for Designing Circuit Board Patterns

Observe the following cautions when designing circuit patterns for this product.

Local Oscillator Circuit (pin 1)

Isolate the local oscillator circuit block sufficiently from the RF amp block.

Isolate the local oscillator circuit block securely so that its output will not get in the IF input, IF filter, or

mixer input.

Do not place the local oscillator circuit block too close to the ceramic filter.

Subdivide the ground pattern for the local oscillator circuit block, and connect the subdivisions with thin

lines.

Mixer Output Block (pin 4) to IF Input Block (pin 6)

Isolate the input and output patterns of the IF filter securely from each other.

Demodulator Circuit Block (pin 10)

Isolate the demodulator circuit block sufficiently from the IF input block (pin 6).

Do not place the LC too close to the IC device.

Data Output Block (pin 12)

Isolate the data output block sufficiently from the IF input block (pin 6).

Isolate the output pattern of the data output block from other circuits as much as possible, so any noise from

a stage subsequent to the output will not affect them.

RF Amp Circuit Block

(1)

Preventing RF amp oscillation

Do not place the patterns connected to pins 13 and 14 too close to each other.

Isolate the patterns connected to the input block (pin 13) and output block (pin 16) from each other.

Make the RF input signal line relatively thin.

Place a relatively wide ground pattern between the RF-IN pin (pin 13) and RF-DEC pin (pin 14).

Connect the RF-OUT pin (pin 16) and MIX-IN pin (pin 18) with the shortest possible pattern.

(2)

Attaining a sufficient gain

To attain a sufficient RF amp gain, select an optimum value for the input matching circuit block

(pin 13) according to the board circuit pattern.

IC Mounting Area

Provide a ground pattern under the IC device, and prepare relatively many through holes.