An apparatus and method for processing signals in the analog domain. A signal is derived from analog circuit properties that is shift and scale invariant. Although the circuit properties are not quantized as in traditional digital signal processing, the signal is immune from effects of the properties, such as common mode noise, absolute voltage or current level, finite settling time, etc., as a digital signal would be. The shift and scale invariance allows for mathematical operations of addition, subtraction, multiplication and division of signals. By combining these operations, various circuits may be constructed, including a voltage controlled amplifier, a time gain amplifier, and an analog-to-digital converter. The circuits are constructed using almost no non-linear, active devices, and will thus use less power for a given speed than comparable digital devices, and will often be faster as there are no delay elements and no need to wait for the circuit properties to settle.

An apparatus and method for processing signals in the analog domain. A signal is derived from analog circuit properties that is shift and scale invariant. Although the circuit properties are not quantized as in traditional digital signal processing, the signal is immune from effects of the properties, such as common mode noise, absolute voltage or current level, finite settling time, etc., as a digital signal would be. The shift and scale invariance allows for mathematical operations of addition, subtraction, multiplication and division of signals. By combining these operations, various circuits may be constructed, including a voltage controlled amplifier, a time gain amplifier, and an analog-to-digital converter. The circuits are constructed using almost no non-linear, active devices, and will thus use less power for a given speed than comparable digital devices, and will often be faster as there are no delay elements and no need to wait for the circuit properties to settle.

A comparator having: a first transistor coupled to a first input terminal; a first current source coupled to the first transistor; a second transistor coupled to a second input terminal and coupled to the first current source; a third transistor coupled in series with the first transistor; a fourth transistor coupled in series with the second transistor; a fifth transistor coupled in series with the first transistor; a sixth transistor coupled in series with the second transistor; a seventh transistor coupled to the first input terminal and coupled as a source follower to the fifth transistor; and an eighth transistor coupled to the second input terminal and coupled as a source follower to the sixth transistor. The comparator also including a differential amplifier coupled to the first output terminal and coupled to the second output terminal.

A circuit includes a gain stage, first and second amplifiers, and a comparison circuit. The gain stage has an input and an output. The first amplifier has an input and an output. The input of the first amplifier is coupled to the input of the gain stage. The second amplifier has an input and an output. The input of the second amplifier is coupled to the output of the gain stage. The comparison circuit is coupled to the outputs of the first and second amplifiers. The comparison circuit is configured to compare signals on the outputs of the first and second amplifiers and to generate a fault flag signal responsive to the output signal from the first amplifier being different than the output signal from the second amplifier.

An example VGA includes a transistor arrangement having a plurality of transistors configured to realize one or more gain step circuits of the VGA, and a cross-couple switching arrangement having a plurality of switches configured to selectively change the coupling of the terminals of at least some of the transistors depending on whether a given gain step circuit is supposed to be in an ON state or in an OFF state. Using the cross-couple switching arrangement advantageously allows keeping all of the transistors ON at all times during operation and changing the coupling of some transistor terminals to either realize an in-phase addition of currents flowing through various transistors to apply the maximum gain or realize a subtraction of currents to apply the minimum gain. Such a VGA may be inherently wideband, enabling a highly linear, wideband operation without having to resort to significant trade-offs with other performance parameters.

In one example an amplifier includes a bias circuit, an open-loop gain stage including a first PMOS having a gate coupled to a first node, a source coupled to a second node, a drain coupled to a third node, and a bulk coupled to the bias circuit, a second PMOS having a gate coupled to a ground node, a source coupled to the second node, a drain coupled to a fourth node, and a bulk coupled to the bias circuit, a first NMOS having a drain and a gate coupled to the third node and a source coupled to a fifth node, a second NMOS having a drain coupled to the fourth node, a gate coupled to the third node, and a source coupled to the fifth node, an adjustable resistor coupleable between the third and fourth nodes, and a buffer stage coupled to the open-loop gain stage.

Distributed amplifiers with controllable linearization are provided herein. In certain embodiments, a distributed amplifier includes a differential input transmission line, a differential output transmission line, and a plurality of differential distributed amplifier stages connected between the differential input transmission line and the differential output transmission line at different points or nodes. The distributed amplifier further includes a differential non-linearity cancellation stage connected between the differential input transmission line and the differential output transmission line and providing signal inversion relative to the differential distributed amplifier stages. The differential non-linearity cancellation stage operates with a separately controllable bias from the differential distributed amplifier stages, thereby providing a mechanism to control the linearity of the distributed amplifier.

A power amplifier circuit includes a first amplifier that amplifies an input signal and outputs an output signal; a second amplifier that, in accordance with a control signal, amplifies a signal corresponding to the input signal, generates a signal having an opposite phase to that of the output signal, and adds the signal to the output signal; and a control circuit that supplies the control signal to the second amplifier. The control circuit outputs the control signal so that during operation of the power amplifier circuit in a first power mode, a gain of the second amplifier is not less than zero and less than a predetermined level and during operation in a second power mode lower than the first power mode in output power level, a gain of the second amplifier is not less than the predetermined level and less than a gain of the first amplifier.

An amplifier includes a first input transistor, a second input transistor, a first current mirror circuit, and a second current mirror circuit. The first input transistor is coupled to a first input terminal. The second input transistor is coupled to a second input terminal. The first current mirror circuit is coupled to the first input transistor and the second input transistor. The second current mirror circuit is coupled to the first input transistor, the second input transistor, and the first current mirror circuit.

In one example an amplifier includes a bias circuit, an open-loop gain stage including a first PMOS having a gate coupled to a first node, a source coupled to a second node, a drain coupled to a third node, and a bulk coupled to the bias circuit, a second PMOS having a gate coupled to a ground node, a source coupled to the second node, a drain coupled to a fourth node, and a bulk coupled to the bias circuit, a first NMOS having a drain and a gate coupled to the third node and a source coupled to a fifth node, a second NMOS having a drain coupled to the fourth node, a gate coupled to the third node, and a source coupled to the fifth node, an adjustable resistor coupleable between the third and fourth nodes, and a buffer stage coupled to the open-loop gain stage.