Abstract: A transimpedance amplifier (TIA) circuit and received signal strength indicator (RSSI) circuit are provided on a same integrated circuit substrate for providing of a TIA output signal and a RSSI signal. The RSSI signal is being used as an indication of optical alignment when aligning of an optical fiber to a photodetector coupled with the TIA during optical receiver manufacture or as received optical signal strength during operation. This allows for the TIA and RSSI circuit to be disposed within an optical signal receiver module prior to optical alignment. The TIA overcomes limitations of the prior art by allowing for a 2V reverse bias voltage to be provided on a PIN diode when the PIN diode is used with a single ended 3.3V supply voltage.

Abstract: Power supply noise affects the performance of many amplifier circuits. Power supply noise rejection circuits are typically used in conjunction with amplifier circuits to reduce the effects of the noise. Unfortunately, the main issue with a transimpedance amplifier (TIA) is that it has a single input port and a single output port, and the output ports are often required to be of a differential type in order to interface with a differential input post amplifier circuit. As a result, the conversion from single input port operation to a dual input port configuration for differential operation is often the cause of poor power supply noise rejection. A circuit is thus provided that overcomes the limitations in the prior art by providing a differential TIA for use with a filter circuit and differential amplifier that overcomes the limitations of the prior art.

Abstract: Transimpedance amplifiers (TIAs) are typically used within optical receiver modules to amplify weak photocurrents received from the photodetector, in the form of photodiode, or a PIN diode. Since TIAs are used to amplify weak photocurrents, noise in the resultant amplification of the weak photocurrent is typically a problem. However, TIAs must not only provide low noise amplification of weak photocurrents, but must also operate when a much higher optical power is received by the photodetector and hence a much higher photocurrent is provided to an input port of the TIA. Of course, with the higher photocurrent received from the photodetector the TIA must also exhibit acceptable bit error rate performance as with the lower photocurrents. An elevated front end TIA (EFTIA) is thus provided that offers low noise performance while providing a wide dynamic range, which overcomes the deficiencies of the prior art.

Abstract: Transimpedance amplifiers (TIAs) are typically used within optical receiver modules to amplify weak photocurrents received from the photodetector. The TIA amplifies this weak photocurrent into an output voltage that is further provided to other stages of the optical receiver module. Since TIAs are used to amplify weak photocurrents, noise in the resultant amplification of the weak photocurrent is typically a problem. However, TIAs must not only provide low noise amplification of weak photocurrents, but must also operate when a much higher optical power is received by the photodetector and hence a much higher photocurrent is provided to an input port of the TIA. An elevated front end TIA (EFTIA) is thus provided that offers low noise performance while providing a wide dynamic range, which overcomes the deficiencies of the prior art. Furthermore, the EFTIA is provided absent a transistor switching circuit.

Abstract: Circuits such as Phase Lock Loops which use VCO's are affected by temperature and power supply variations which effect the performance of the circuit, particularly at high frequencies and low supply voltages. The present invention provides a variable delay circuit stage comprising one or more delay stages and an analogue multiplexer arranged to control the amount of delay introduced by the delay stages; a supply voltage pushing compensation circuit stage comprising a transconductance stage connected to the multiplexer and arranged to produce a compensating current upon deviation from nominal supply voltage which changes said delay; and a temperature pushing compensation circuit stage comprising a transconductance stage connected to the multiplexer and arranged to produce a compensating current upon deviation from nominal temperature which changes said delay.