An apparatus includes a first circuit and a second circuit. The first circuit may be configured to generate (i) a variable current and (ii) a constant current. The variable current may be proportional to a temperature of the first circuit. The second circuit may be configured to present a resistance through a plurality of first transistors between two ports in response to both the variable current and the constant current. The resistance may have a predefined dependence on the temperature.

A bias circuit for a bipolar RF amplifier is described. The bias circuit includes a current source coupled to a bias network. The bias network supplies a base current to the transistors in the amplifier circuit of the bipolar RF amplifier. The bias circuit includes a buffer coupled to the bias network and to the bipolar RF amplifier. The buffer provides additional base current to the amplifier circuit of bipolar RF amplifier and sinks avalanche current generated by the amplifier circuit of the bipolar RF amplifier.

Described herein are systems and methods that can adjust the performance of a transimpedance amplifier (TIA) in order to compensate for changing environmental and/or manufacturing conditions. In some embodiments, the changing environmental and/or manufacturing conditions may cause a reduction in beta of a bipolar junction transistor (BJT) in the TIA. A low beta may result in a high base current for the BJT causing the output voltage of the TIA to be formatted as an unusable signal output. To compensate for the low beta, the TIA generates an intermediate signal voltage, based on the base current and beta that is compared with the PN junction bias voltage on another BJT. Based on the comparison, the state of a digital state machine may be incremented, and a threshold base current is determined. This threshold base current may decide whether to compensate the operation of the TIA, or discard the chip.

A bias current circuit includes: an N-type MOSFET in which a gate terminal and a drain terminal are connected to a current source, and N-type MOSFETs in which respective drain terminals are connected to respective bias current output terminals and source terminals are grounded. The bias current circuit further includes: an N-type MOSFET in which one terminal type, either a drain terminal or a source terminal, is connected to the gate terminal of the N-type MOSFET, and the other terminal type is connected to the gate terminals of the N-type MOSFETs, and an N-type MOSFET in which a drain terminal is connected to the gate terminals of the N-type MOSFETs and a source terminal is grounded. A control signal, that is LOW when the bias current is supplied and is HIGH when the bias current is not supplied, is input to the gate terminal of the N-type MOSFET, and an inverse signal of the control signal is input to the gate terminal of the N-type MOSFET.

A voltage-to-current converter can be configured to generate a current based on an input voltage and for part of the time use the generated current as the output current of the voltage-to-current converter, and for part of the time use the generated current as a current source for the operation of the voltage-to-current converter. This arrangement can reduce the need for high performance current mirror circuits within the voltage-to-current converter, thereby reducing the cost and complexity of the voltage-to-current converter and improving precision and accuracy.

A bias current circuit includes: an N-type MOSFET in which a gate terminal and a drain terminal are connected to a current source, and N-type MOSFETs in which respective drain terminals are connected to respective bias current output terminals and source terminals are grounded. The bias current circuit further includes: an N-type MOSFET in which one terminal type, either a drain terminal or a source terminal, is connected to the gate terminal of the N-type MOSFET, and the other terminal type is connected to the gate terminals of the N-type MOSFETs, and an N-type MOSFET in which a drain terminal is connected to the gate terminals of the N-type MOSFETs and a source terminal is grounded. A control signal, that is LOW when the bias current is supplied and is HIGH when the bias current is not supplied, is input to the gate terminal of the N-type MOSFET, and an inverse signal of the control signal is input to the gate terminal of the N-type MOSFET.

An electric circuit according to one embodiment of the present technology includes a target circuit and an auxiliary circuit. The target circuit includes an output portion from which predetermined output power is output, and an application point to which a voltage corresponding to the output power is applied to output the output power. The auxiliary circuit has impedance lower than impedance of the target circuit, and outputs the voltage corresponding to the output power to the application point as an auxiliary voltage.

A constant current generation circuit for optocoupler isolation amplifier and a current precision adjustment method are provided. The constant current generation circuit includes a start circuit, a current generation circuit and a precision adjustment and output circuit integrated into a same substrate. The start circuit can generate and output a first start current and a second start current. The current generation circuit includes a negative temperature change rate current generation circuit connected to a first start current output and a positive temperature change rate current generation circuit connected to a second start current output. The precision adjustment and output circuit outputs constant current meeting application requirements of optocoupler isolation amplifier by adjusting proportional precision of two currents output from a current generation circuit.

An amplification apparatus includes a bias circuit for supplying a bias voltage, and an amplification circuit to which the bias voltage is supplied from the bias circuit. The bias circuit includes a first current source for increasing/decreasing a first current depending on the bias voltage, and a first MOSFET with first polarity through which the first current flows, to output a first voltage from a connection between the first current source and the first MOSFET; a second current source for outputting a constant current as a second current, and a second MOSFET with second polarity through which the second current flows, to output a second voltage from a connection between the second current source and the second MOSFET; and a voltage comparator for increasing/decreasing the bias voltage such that the first and second voltages become equal, based on a difference between the first and second voltages.

An amplification apparatus includes a bias circuit for supplying a bias voltage, and an amplification circuit to which the bias voltage is supplied from the bias circuit. The bias circuit includes a first current source for increasing/decreasing a first current depending on the bias voltage, and a first MOSFET with first polarity through which the first current flows, to output a first voltage from a connection between the first current source and the first MOSFET; a second current source for outputting a constant current as a second current, and a second MOSFET with second polarity through which the second current flows, to output a second voltage from a connection between the second current source and the second MOSFET; and a voltage comparator for increasing/decreasing the bias voltage such that the first and second voltages become equal, based on a difference between the first and second voltages.