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.

An example current mirror arrangement includes a current mirror circuit, configured to receive an input current signal at an input transistor Q1 and output a mirrored signal at an output transistor Q2. The arrangement further includes a semi-cascoding circuit that includes transistors Q3, Q4, and a two-terminal passive network. The transistor Q3 is coupled to, and forms a cascode with, the output transistor Q2. The transistor Q4 is coupled to the transistor Q3. The base/gate of the transistor Q3 is coupled to a bias voltage Vref, and the base/gate of the transistor Q4 is coupled to a bias voltage Vref1 via the two-terminal passive network. Nonlinearity of the output current from such a current mirror arrangement may be reduced by selecting appropriate impedance of the two-terminal passive network and selecting appropriate bias voltages Vref and Vref1.

Voltage-to-current converters that include two current mirrors are disclosed. In an example voltage-to-current converter each current mirror is a complementary current mirror in that one of its input and output transistors is a P-type transistor and the other one is an N-type transistor. Such voltage-to-current converters may be implemented using bipolar technology, CMOS technology, or a combination of bipolar and CMOS technologies, and may be made sufficiently compact and accurate while operating at sufficiently low voltages and consuming limited power.

A multi-stage transimpedance amplifier (TIA) with an adjustable input linear range is disclosed. The TIA includes a first stage, configured to convert a single-ended current signal from an optical sensor of a receiver signal chain to a single-ended voltage signal, and a second stage, configured to convert the single-ended voltage signal provided by the first stage to a differential signal. In such a TIA, the input linear range may be adjusted using a clamp that is programmable with an output offset current to keep the second stage of the TIA from overloading and to maintain a linear transfer function without compression.

A multi-stage amplifier including a pre-driver stage, and method of operating the same. In one example, the amplifier includes an output stage with a first output transistor coupled to an oppositely doped second output transistor and to an output terminal. The pre-driver stage includes with a first driver transistor coupled to the first output transistor, and a second driver transistor coupled to the second output transistor. The pre-driver stage also includes a first current mirror and a second current mirror coupled to the first driver transistor and the second driver transistor. The pre-driver stage also includes a first translinear loop having a first translinear loop transistor and a second translinear loop having a second translinear loop transistor coupled to the first output transistor and the second output transistor.

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 multi-stage amplifier including a pre-driver stage, and method of operating the same. In one example, the amplifier includes an output stage with a first output transistor coupled to an oppositely doped second output transistor and to an output terminal. The pre-driver stage includes with a first driver transistor coupled to the first output transistor, and a second driver transistor coupled to the second output transistor. The pre-driver stage also includes a first current mirror and a second current mirror coupled to the first driver transistor and the second driver transistor. The pre-driver stage also includes a first translinear loop having a first translinear loop transistor and a second translinear loop having a second translinear loop transistor coupled to the first output transistor and the second output transistor.

According to one aspect, embodiments of the invention provide a distortion detection circuit comprising an input configured to be coupled to an output stage of an amplifier and to receive an RF signal from the output stage of the amplifier, an output configured to be coupled to a module of the amplifier, at least one peak detection circuit coupled to the input and configured to monitor the RF signal and output a first signal based on positive voltage peaks of the RF signal, and a differential amplifier having an input coupled to the at least one peak detection circuit and configured to monitor the first signal and provide a second signal to the output in response to a voltage of the first signal exceeding a threshold level indicative of distortion in the RF signal.

A multi-stage transimpedance amplifier (TIA) with an adjustable input linear range is disclosed. The TIA includes a first stage, configured to convert a single-ended current signal from an optical sensor of a receiver signal chain to a single-ended voltage signal, and a second stage, configured to convert the single-ended voltage signal provided by the first stage to a differential signal. In such a TIA, the input linear range may be adjusted using a clamp that is programmable with an output offset current to keep the second stage of the TIA from overloading and to maintain a linear transfer function without compression.

Voltage-to-current converters that include two current mirrors are disclosed. In an example voltage-to-current converter each current mirror is a complementary current mirror in that one of its input and output transistors is a P-type transistor and the other one is an N-type transistor. Such voltage-to-current converters may be implemented using bipolar technology, CMOS technology, or a combination of bipolar and CMOS technologies, and may be made sufficiently compact and accurate while operating at sufficiently low voltages and consuming limited power.