摘要:
A gain switching circuit (3) that switches a conversion gain of a preamp (2), which outputs a voltage signal upon amplifying an output current of a photo-detecting element (1) that converts a burst-form optical signal into an electrical signal and with which a series circuit, formed with a first resistor (6) and a first switching element (9), and a series circuit, formed with a second resistor (7) and a second switching element (10), are connected in parallel to a feedback resistor (2B), generates an operating signal for closing the first switching element (9) within a first gain switching period and generates an operating signal for closing the second switching element (10) within a second gain switching period.
摘要:
Die Erzeugung einer Widerstandseinstellung entsprechend einem vorgegebenen Spannungswert läßt sich ohne Verzerrung, Dynamikbeschneidung oder sonstige Störungen für das durch den Widerstand beeinflußte signal erzielen, wenn ein zwei Eingänge aufweisender Regelkreis (4,12) vorgesehen ist, dessen Eingangssignale sich im eingeregelten Zustand einander entsprechend, wovon ein Eingangssig- 'nal durch den vorgegebenen Spannungswert (U DAC ) gebildet und das zweite Eingangssignal über einem lichtabhängigen Widerstand (6) abnehmbar ist, wenn das Ausgangssignal des Regelkreises (4,12) eine zu dem lichtabhängigen Widerstand (6) gehörende und mit ihm ein Leuchtdioden-Widerstand-Paar (12) bildende Leuchtdiode (10) steuert und wenn das Ausgangssignal des Regelkreises (4,12) die Leuchtdiode eines weiteren Leuchtdioden-Widerstand-Paares (14) steuert, dessen Widerstand (13) somit entsprechend dem vorgegebenen Spannungswert (U PAC ) eingestellt ist.
摘要:
Die Erzeugung einer Widerstandseinstellung entsprechend einem vorgegebenen Spannungswert läßt sich ohne Verzerrung, Dynamikbeschneidung oder sonstige Störungen für das durch den Widerstand beeinflußte signal erzielen, wenn ein zwei Eingänge aufweisender Regelkreis (4,12) vorgesehen ist, dessen Eingangssignale sich im eingeregelten Zustand einander entsprechend, wovon ein Eingangssig- 'nal durch den vorgegebenen Spannungswert (U DAC ) gebildet und das zweite Eingangssignal über einem lichtabhängigen Widerstand (6) abnehmbar ist, wenn das Ausgangssignal des Regelkreises (4,12) eine zu dem lichtabhängigen Widerstand (6) gehörende und mit ihm ein Leuchtdioden-Widerstand-Paar (12) bildende Leuchtdiode (10) steuert und wenn das Ausgangssignal des Regelkreises (4,12) die Leuchtdiode eines weiteren Leuchtdioden-Widerstand-Paares (14) steuert, dessen Widerstand (13) somit entsprechend dem vorgegebenen Spannungswert (U PAC ) eingestellt ist.
摘要:
A photodetector (1) converts an optical signal in the form of a burst into an electrical signal and outputs an output current, and a preamplifier (2) having a feedback resistive element (2B) amplifies the output current and outputs a voltage signal. The feedback resistive element (2B), a series circuit of a first resistive element (6) and a first switching element (9), and a series circuit of a second resistive element (7) and a second switching element (10) are connected in parallel to a gain varying circuit (3) for varying the conversion gain of the preamplifier (2). The gain varying circuit (3) generates an operation signal to close the first switching element 9 during a first gain varying period and an operation signal to close the second switching element (10) during a second gain varying period.
摘要:
An active avalanche photo-diode, APD, gain control circuit for use in an optical receiver includes a bias generator for varying the bias on a variable gain APD in response to bias control values generated by a controller. The controller receives the output of the optical receiver and determines the system noise of the receiver for the various bias control values. The system noise is compared to a threshold value for establishing the optimum bias for optimum gain of the APD. The gain control circuit is useable in an optical receiver in an optical time domain reflectometer, OTDR, for increasing the dynamic range of the OTDR.
摘要:
A gain switching circuit (3) that switches a conversion gain of a preamp (2) , which outputs a voltage signal upon amplifying an output current of a photo-detecting element (1) that converts a burst-form optical signal into an electrical signal and with which a series circuit, formed with a first resistor (6) and a first switching element (9) , and a series circuit, formed with a second resistor (7) and a second switching element (10) are connected in parallel to a feedback resistor (2B). The switching circuit further includes a gate signal generating circuit that generates, upon receiving an output of the pre-amplifier, a gate signal for a first and second operating unit.
摘要:
A magnetic verification system for bill acceptor including a magnetic induction circuit, a signal amplifying and regulating circuit, and a magnetic field generating circuit, the signal amplifying and regulating circuit having a D/A converter, the magnetic induction circuit having a magnetic device adapted for scanning the magnetic ink of the bill to be verified, the magnetic device being adapted to write a magnetic field reference value from the magnetic field generating circuit into the D/A converter, for enabling the D/A converter to adjust the intensity of light being emitted by a LED of the signal amplifying and regulating circuit onto a photoresistance of the signal amplifying and regulating circuit so as to cause the photoresistance to change the resistance thereof subject to the intensity of light from the LED, so that an operation amplifier at the output end of the magnetic induction circuit obtains the correct magnetic field signal value to verify the authenticity of the inserted bill.