1998 Jul 08

5

Philips Semiconductors

Objective specification

SDH/SONET STM1/OC3 transimpedance amplifier

TZA3033

Pad centre locations

Note

1. All coordinates (

µm) are measured with respect to the

bottom left-hand corner of the die.

SYMBOL

PAD

xy

DREF

1

95

881

TESTA

2

95

735

GND

3

95

618

GND

4

95

473

IPhoto

5

95

285

TESTB

6

95

147

GND

7

215

95

GND

8

360

95

GND

9

549

95

GND

10

691

95

OUT

11

785

501

OUTQ

12

785

641

13

567

1055

14

424

1055

AGC

15

259

1055

FUNCTIONAL DESCRIPTION

The TZA3033 is a transimpedance amplifier intended for

use in fibre optic links for signal recovery in STM1/OC3

applications. It amplifies the current generated by a photo

detector (PIN diode or avalanche photodiode) and

transforms it into a differential output voltage. The most

important characteristics of the TZA3033 are high receiver

sensitivity and wide dynamic range.

High receiver sensitivity is achieved by minimizing noise in

the transimpedance amplifier.

The signal current generated by a PIN diode can vary

between 0.25

µA to 1.6 mA (peak-to-peak value).

An AGC loop (see Fig.1) is implemented to make it

possible to handle such a wide dynamic range.

The AGC loop increases the dynamic range of the

receiver by reducing the feedback resistance of the

preamplifier. The AGC loop hold capacitor is integrated

on-chip, so an external capacitor is not needed for AGC.

The AGC voltage can be monitored at pad 15 on the naked

die (TZA3033U). Pad 15 is not bonded in the packaged

device (TZA3033T). This pad can be left unconnected

during normal operation. It can also be used to force an

external AGC voltage. If pad 15 (AGC) is connected to

gain is at a maximum. The maximum input current is then

about 10

µA.

A differential amplifier converts the output of the

preamplifier to a differential voltage. The data output circuit

is given in Fig.4.

The logic level symbol definitions are shown in Fig.5.