JPH02284477A - Semiconductor photodetecting device - Google Patents

Abstract

PURPOSE:To apparently reduce a necessary bias voltage to about one-half, and form a semiconductor photodetecting device easy to be used by constituting a driving circuit for ADP bias in a monolithic type, and mounting it on the same package as an ADP chip. CONSTITUTION:When outputs from a buffer Ib1 and a buffer Ib2 are input to a voltage multiplier, the input signal viewed from the voltage multiplier 2 fluctuates in a pulse between voltages VCC and VEE. When +VCC inputs, a transistor TR Q1 turns ON, a TR Q2 turns OFF, a TR Q3 turns OFF, and a TR Q4 turns ON. The charging current flows in the order of Q1 C2 D2 C 3 Q4. At this time, the charging voltage of a capacitor C3 becomes a value wherein the charged voltage of the capacitor C2 is added to the emitter potential of the TR Q1, because the capacitor C2 has been already charged. As a result, a voltage of 2X¦CC-VEE¦ is applied to the capacitor C3. Thereby a bias voltage necessary to a conventional avalanche photo diode ADP can be reduced apparently to about one-half.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor light receiving device.

[Conventional technology]

The conventional avalanche photodiode (APD) of a semiconductor photodetector for optical communication is simply exposed with its terminals protruding from the avalanche photodiode (APD). 200-300V for germanium APD, 20-50V for InGaA
In the case of s APD, a high bias voltage of 50 to 80 cm (depending on the multiplication factor used) is required, making it difficult to use.

[Invention or problem to be solved]

The conventional avalanche photodiodes 1 to 1 described above have the drawback of requiring a high bias voltage and being difficult to use.

[Means to solve the problem]

The semiconductor light receiving device of the present invention includes an oscillation circuit of an unstable multi-hyflator type, a first buffer and a second buffer that are respectively connected to the output ends of the oscillation circuit and operate complementary to each other, and the first buffer. and a drive circuit chip that integrates a voltage doubler circuit for rectifying the voltage between the output terminals of the first and second buffers, and an avalanche photo-tire auto chip connected to the drive circuit chip.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

Inverter ■1, inverter ■2, and resistor RF.

A feedback circuit including R1 and capacitor C1 constitutes an unstable multivibrator type oscillation circuit 1a. As a result, the output voltage of inverter ■2 is approximately "-■cc
The pulse operation is repeated between and -1-V Bp. Furthermore, the pulse signal (AC signal) is transmitted to the transistors Q], , Q2 and C4, respectively.
first buffer 1-bl, second buffer of Temball type), b2 to reduce the output impedance. In this case, the voltage value does not change significantly compared to the output of the previous stage oscillation circuit.

In addition, the first buffer 1 b ] and the second buffer 1,
The output from l:+2 is input to the voltage doubler circuit 2.

By doing this, the input signal seen from the voltage doubler circuit 2 is approximately ■. It fluctuates like a pulse between C and VEE. For example, when vl is input, Ql is off, C2 is on, C3 is on, and C4 is off (Ql to Q4 are all operated in the switching region), and the charging current changes from C3 → D1 →
The power flows in the order of C2→Q2 and charges C2. Next time +VCC is input, Ql is on, C2 is off, C3
is off, C4 is on, and the charging current is Q]→C2
The charging voltage of C3 at this time, which will flow in the order of → D2 → C3 → Q4, is because C2 has already been charged.
This is the sum of the emic potential of Ql and the charging voltage of C2, and a first voltage of approximately 2×1 VccV is applied.

By adding the above circuit, it becomes possible to reduce the voltage used as a bias for a conventional APD by approximately half.

Incidentally, FIG. 2 shows an example in which the above-mentioned drive circuit is made into a monolithic IC and mounted on one type of chip carrier together with an APD chip. A light-shielding coating film 3 (synthetic resin mixed with black powder and coated) is placed on the drive circuit chip 4. 1.6, 1.7.18 are output terminal metallized layers corresponding to output terminals 5, 6.7.

〔Effect of the invention〕

As explained above, the present invention makes the APD bias drive circuit a monolithic IC and assembles it in the same package as the APD chip, thereby reducing the bias voltage required for conventional APDs by approximately half, making the semiconductor photodetector device easy to use. There is an effect that can be obtained.

12... VCC electrode metal rice layer, ]3... Light-shielding coach ink film, ]4... Drive circuit chip, ]5... API
Chip, ], 6.17.1.8... Output terminal metal rice layer, 19-V cc electrode metal rice layer, C1,, C2
C5... Capacitor, D], C2... Taioh 1~
, RI R2, RF...resistance, Ql-, C4...N
PN) transistor, C2, C3...PNP l-transistor.

Claims (1)

[Claims] an unstable multivibrator type oscillation circuit, a first buffer and a second buffer each connected to the output terminal of the oscillation circuit and operating in a complementary manner to each other, and between the output terminals of the first buffer and the second buffer; 1. A semiconductor light-receiving device comprising: a drive circuit chip that integrates a voltage doubler circuit for rectifying a voltage; and an avalanche photodiode chip connected to the drive circuit chip.