TK14551V View Datasheet(PDF) - Toko America Inc
Part Name
Description
Manufacturer
TK14551V Datasheet PDF : 32 Pages
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TK14551V
CIRCUIT DESCRIPTION
IF Limiter Amplifier:
The IF limiter amplifier is composed of four differential gain stages. The total gain of the IF limiter amplifier is about 64
dB. The output signal of the IF limiter amplifier is provided at Pin 3 through the emitter-follower output stage. The IF limiter
amplifier output level is 0.5 VP-P.
The operating current of the IF limiter amplifier emitter-follower output is 550 µA. If the capacitive load is heavy, the
negative half cycle of the output waveform may be distorted. This distortion can be reduced by connecting an external
resistor between Pin 3 and GND to increase the operating current. The increased operating current by using an external
resistor is calculated as follows (see Figure 1):
VCC
IF OUTPUT
Re
Ie
FIGURE 1
The increased operating current Ie (mA) = (VCC - 1.0)/Re (kΩ).
Because the IF input is a balanced input, it is easy to match a SAW filter, etc.
If the IF input is an unbalanced input, connect Pin 23 or 24 with a bypass capacitor to ground.
The input resistance of the IF limiter amplifier is 1.5 kΩ (see Figure 2). If the impedance of the filter is lower than 1.5 kΩ,
connect an external resistor between Pin 24 and Pin 2 or between Pin 23 and Pin 1 in parallel to provide the equivalent
load impedance of the filter. Figure 2 shows an example of a filter with a 330 Ω impedance.
23,
24
330
1.5 K
1, 2
FIGURE 2
January 2000 TOKO, Inc.
Page 19
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