Printed circuit layout

TSH93

8/13

4

Printed circuit layout

As for any high frequency device, a few rules must be observed when designing the PCB to

get the best performance from this high speed op-amp.

From the most important to the least important point:

●

Each power supply lead must be bypassed to ground with a 10nF ceramic capacitor

very close to the device and a 10

μF capacitor.

●

To provide low inductance and low resistance common return, use a ground plane or

common point return for power and signal.

●

All leads must be wide and as short as possible especially for op-amp inputs. This is in

order to decrease parasitic capacitance and inductance.

●

Use small resistor values to decrease the time constant with parasitic capacitance.

●

Choose component sizes as small as possible (SMD).

On output, decrease capacitor load to avoid degradation in circuit stability which may cause

oscillation. You can also add a serial resistor in order to minimize its influence.

Figure 12.

Differential input impedance vs.

frequency

Figure 13.

Common input impedance vs.

frequency

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

1k

10k

100k

1M

10M

100M

Frequency (Hz)

1k

10k

100k

1M

10M

100M

Frequency (Hz)

120

100

80

60

40

20