Optical receiver
A technology of optical receivers and optical receiving components, applied in electromagnetic receivers, electromagnetic transceivers, transmission systems, etc., can solve the problems of increasing chip area and increasing the number of parts, so as to prevent the increase of parasitic capacitance, reduce the flow current, and suppress The effect of the increase in output pulse amplitude distortion
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Embodiment 1
[0045] figure 1 It is a block diagram showing the optical receiver 1 of this embodiment. The light receiving element 11 converts an optical signal transmitted from the outside through an optical fiber cable or the like into an electric current signal. The current signal of the light receiving element passes through the low frequency and high frequency current separating filter circuit (filter circuit) 12, and is separated into a low frequency current component approximated to a DC component of the current signal and a high frequency current component including a data sequence.
[0046] The low-frequency current component is input to the comparator 14 through the current-voltage conversion circuit 13 for current-voltage conversion, and then input to the bias circuit 15 .
[0047] use figure 2 The current component of the light receiving element will be described in more detail. figure 2 The current waveform of the light-receiving element is the waveform when a bi-phase sy...
Embodiment 2
[0054] As shown in FIG. 3, the modulated optical signal is converted into a current signal by the light receiving element PD1. When the optical receiver is on standby, the gate voltage of the N-channel MOSFET (MN1) becomes a high level, and since MN1 is turned on, one electrode of the capacitor C1 is grounded to the GND level. The low frequency component of the current flowing in the light receiving element flows through the resistor R1 and the high frequency component flows through the capacitor C1 through the filter circuit composed of the resistor R1 and the capacitor C1 connected to the ground through the MN1. Specifically, the current flowing through resistor R1
[0055] fc=1 / {2π·(R1+Vt / IDC_PD)·C1}
[0056] (in,
[0057] Vt: k·T / q
[0058] k: Boltzmann constant
[0059] T: absolute temperature
[0060] q: elementary charge
[0061] IDC_PD: A DC current component flowing through the light receiving element PD1) becomes a current signal passing through a low-pass filt...
Embodiment 3
[0072] Such as Figure 4 As shown, on the structure of Fig. 3, the low-frequency current flowing in the light receiving element PD1 is amplified by the current mirror composed of PNP transistors QP1 and QP4, and the voltage is converted by the resistor R mon, so that it is output to the Monitor (MON ITOR) terminal. Thereby, the intensity of the light signal incident on the light receiving element PD1 can be monitored. In addition, the receiver can enter the operation mode only when the optical signal incident on the light-receiving element is within a certain range due to the combination of the window comparator through the multi-segment current mirror.
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